Class

org.scalatest

AsyncFunSuite

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abstract class AsyncFunSuite extends AsyncFunSuiteLike

Enables testing of asynchronous code without blocking, using a style consistent with traditional FunSuite tests.

Recommended Usage: AsyncFunSuite is intended to enable users of FunSuite to write non-blocking asynchronous tests that are consistent with their traditional FunSuite tests. Note: AsyncFunSuite is intended for use in special situations where non-blocking asynchronous testing is needed, with class FunSuite used for general needs.

Given a Future returned by the code you are testing, you need not block until the Future completes before performing assertions against its value. You can instead map those assertions onto the Future and return the resulting Future[Assertion] to ScalaTest. The test will complete asynchronously, when the Future[Assertion] completes.

Here's an example AsyncFunSuite:

package org.scalatest.examples.asyncfunsuite

import org.scalatest.AsyncFunSuite
import scala.concurrent.Future

class AddSuite extends AsyncFunSuite {

  def addSoon(addends: Int*): Future[Int] = Future { addends.sum }

  test("addSoon will eventually compute a sum of passed Ints") {
    val futureSum: Future[Int] = addSoon(1, 2)
    // You can map assertions onto a Future, then return
    // the resulting Future[Assertion] to ScalaTest:
    futureSum map { sum => assert(sum == 3) }
  }

  def addNow(addends: Int*): Int = addends.sum

  test("addNow will immediately compute a sum of passed Ints") {
    val sum: Int = addNow(1, 2)
    // You can also write synchronous tests, which
    // must result in type Assertion:
    assert(sum == 3)
  }
}

test” is a method, defined in AsyncFunSuite, which will be invoked by the primary constructor of AddSuite. You specify the name of the test as a string between the parentheses, and the test code itself between curly braces. The test code is a function passed as a by-name parameter to test, which registers it for later execution. The result type of the by-name in an AsyncFunSuite must be Future[Assertion].

Starting with version 3.0.0, ScalaTest assertions and matchers have result type Assertion. The result type of the first test in the example above, therefore, is Future[Assertion]. For clarity, here's the relevant code in a REPL session:

scala> import org.scalatest._
import org.scalatest._

scala> import Assertions._
import Assertions._

scala> import scala.concurrent.Future
import scala.concurrent.Future

scala> import scala.concurrent.ExecutionContext
import scala.concurrent.ExecutionContext

scala> implicit val executionContext = ExecutionContext.Implicits.global
executionContext: scala.concurrent.ExecutionContextExecutor = [email protected]

scala> def addSoon(addends: Int*): Future[Int] = Future { addends.sum }
addSoon: (addends: Int*)scala.concurrent.Future[Int]

scala> val futureSum: Future[Int] = addSoon(1, 2)
futureSum: scala.concurrent.Future[Int] = [email protected]

scala> futureSum map { sum => assert(sum == 3) }
res0: scala.concurrent.Future[org.scalatest.Assertion] = [email protected]

The second test has result type Assertion:

scala> def addNow(addends: Int*): Int = addends.sum
addNow: (addends: Int*)Int

scala> val sum: Int = addNow(1, 2)
sum: Int = 3

scala> assert(sum == 3)
res1: org.scalatest.Assertion = Succeeded

When AddSuite is constructed, the second test will be implicitly converted to Future[Assertion] and registered. The implicit conversion is from Assertion to Future[Assertion], so you must end synchronous tests in some ScalaTest assertion or matcher expression. If a test would not otherwise end in type Assertion, you can place succeed at the end of the test. succeed, a field in trait Assertions, returns the Succeeded singleton:

scala> succeed
res2: org.scalatest.Assertion = Succeeded

Thus placing succeed at the end of a test body will satisfy the type checker:

  test("addNow will immediately compute a sum of passed Ints") {
    val sum: Int = addNow(1, 2)
    assert(sum == 3)
    println("hi") // println has result type Unit
    succeed       // succeed has result type Assertion
  }

An AsyncFunSuite's lifecycle has two phases: the registration phase and the ready phase. It starts in registration phase and enters ready phase the first time run is called on it. It then remains in ready phase for the remainder of its lifetime.

Tests can only be registered with the test method while the AsyncFunSuite is in its registration phase. Any attempt to register a test after the AsyncFunSuite has entered its ready phase, i.e., after run has been invoked on the AsyncFunSuite, will be met with a thrown TestRegistrationClosedException. The recommended style of using AsyncFunSuite is to register tests during object construction as is done in all the examples shown here. If you keep to the recommended style, you should never see a TestRegistrationClosedException.

Asynchronous execution model

AsyncFunSuite extends AsyncTestSuite, which provides an implicit scala.concurrent.ExecutionContext named executionContext. This execution context is used by AsyncFunSuite to transform the Future[Assertion]s returned by each test into the FutureOutcome returned by the test function passed to withFixture. This ExecutionContext is also intended to be used in the tests, including when you map assertions onto futures.

On both the JVM and Scala.js, the default execution context provided by ScalaTest's asynchronous testing styles confines execution to a single thread per test. On JavaScript, where single-threaded execution is the only possibility, the default execution context is scala.scalajs.concurrent.JSExecutionContext.Implicits.queue. On the JVM, the default execution context is a serial execution context provided by ScalaTest itself.

When ScalaTest's serial execution context is called upon to execute a task, that task is recorded in a queue for later execution. For example, one task that will be placed in this queue is the task that transforms the Future[Assertion] returned by an asynchronous test body to the FutureOutcome returned from the test function. Other tasks that will be queued are any transformations of, or callbacks registered on, Futures that occur in your test body, including any assertions you map onto Futures. Once the test body returns, the thread that executed the test body will execute the tasks in that queue one after another, in the order they were enqueued.

ScalaTest provides its serial execution context as the default on the JVM for three reasons. First, most often running both tests and suites in parallel does not give a significant performance boost compared to just running suites in parallel. Thus parallel execution of Future transformations within individual tests is not generally needed for performance reasons.

Second, if multiple threads are operating in the same suite concurrently, you'll need to make sure access to any mutable fixture objects by multiple threads is synchronized. Although access to mutable state along the same linear chain of Future transformations need not be synchronized, this does not hold true for callbacks, and in general it is easy to make a mistake. Simply put: synchronizing access to shared mutable state is difficult and error prone. Because ScalaTest's default execution context on the JVM confines execution of Future transformations and call backs to a single thread, you need not (by default) worry about synchronizing access to mutable state in your asynchronous-style tests.

Third, asynchronous-style tests need not be complete when the test body returns, because the test body returns a Future[Assertion]. This Future[Assertion] will often represent a test that has not yet completed. As a result, when using a more traditional execution context backed by a thread-pool, you could potentially start many more tests executing concurrently than there are threads in the thread pool. The more concurrently execute tests you have competing for threads from the same limited thread pool, the more likely it will be that tests will intermitently fail due to timeouts.

Using ScalaTest's serial execution context on the JVM will ensure the same thread that produced the Future[Assertion] returned from a test body is also used to execute any tasks given to the execution context while executing the test body—and that thread will not be allowed to do anything else until the test completes. If the serial execution context's task queue ever becomes empty while the Future[Assertion] returned by that test's body has not yet completed, the thread will block until another task for that test is enqueued. Although it may seem counter-intuitive, this blocking behavior means the total number of tests allowed to run concurrently will be limited to the total number of threads executing suites. This fact means you can tune the thread pool such that maximum performance is reached while avoiding (or at least, reducing the likelihood of) tests that fail due to timeouts because of thread competition.

This thread confinement strategy does mean, however, that when you are using the default execution context on the JVM, you must be sure to never block in the test body waiting for a task to be completed by the execution context. If you block, your test will never complete. This kind of problem will be obvious, because the test will consistently hang every time you run it. (If a test is hanging, and you're not sure which one it is, enable slowpoke notifications.) If you really do want to block in your tests, you may wish to just use a traditional FunSuite with ScalaFutures instead. Alternatively, you could override the executionContext and use a traditional ExecutionContext backed by a thread pool. This will enable you to block in an asynchronous-style test on the JVM, but you'll need to worry about synchronizing access to shared mutable state.

To use a different execution context, just override executionContext. For example, if you prefer to use the runNow execution context on Scala.js instead of the default queue, you would write:

// on Scala.js
implicit override def executionContext =
    scala.scalajs.concurrent.JSExecutionContext.Implicits.runNow

If you prefer on the JVM to use the global execution context, which is backed by a thread pool, instead of ScalaTest's default serial execution contex, which confines execution to a single thread, you would write:

// on the JVM (and also compiles on Scala.js, giving
// you the queue execution context)
implicit override def executionContext =
    scala.concurrent.ExecutionContext.Implicits.global

Serial and parallel test execution

By default (unless you mix in ParallelTestExecution), tests in an AsyncFunSuite will be executed one after another, i.e., serially. This is true whether those tests return Assertion or Future[Assertion], no matter what threads are involved. This default behavior allows you to re-use a shared fixture, such as an external database that needs to be cleaned after each test, in multiple tests in async-style suites. This is implemented by registering each test, other than the first test, to run as a continuation after the previous test completes.

If you want the tests of an AsyncFunSuite to be executed in parallel, you must mix in ParallelTestExecution and enable parallel execution of tests in your build. You enable parallel execution in Runner with the -P command line flag. In the ScalaTest Maven Plugin, set parallel to true. In sbt, parallel execution is the default, but to be explicit you can write:

parallelExecution in Test := true // the default in sbt

On the JVM, if both ParallelTestExecution is mixed in and parallel execution is enabled in the build, tests in an async-style suite will be started in parallel, using threads from the Distributor, and allowed to complete in parallel, using threads from the executionContext. If you are using ScalaTest's serial execution context, the JVM default, asynchronous tests will run in parallel very much like traditional (such as FunSuite) tests run in parallel: 1) Because ParallelTestExecution extends OneInstancePerTest, each test will run in its own instance of the test class, you need not worry about synchronizing access to mutable instance state shared by different tests in the same suite. 2) Because the serial execution context will confine the execution of each test to the single thread that executes the test body, you need not worry about synchronizing access to shared mutable state accessed by transformations and callbacks of Futures inside the test.

If ParallelTestExecution is mixed in but parallel execution of suites is not enabled, asynchronous tests on the JVM will be started sequentially, by the single thread that invoked run, but without waiting for one test to complete before the next test is started. As a result, asynchronous tests will be allowed to complete in parallel, using threads from the executionContext. If you are using the serial execution context, however, you'll see the same behavior you see when parallel execution is disabled and a traditional suite that mixes in ParallelTestExecution is executed: the tests will run sequentially. If you use an execution context backed by a thread-pool, such as global, however, even though tests will be started sequentially by one thread, they will be allowed to run concurrently using threads from the execution context's thread pool.

The latter behavior is essentially what you'll see on Scala.js when you execute a suite that mixes in ParallelTestExecution. Because only one thread exists when running under JavaScript, you can't "enable parallel execution of suites." However, it may still be useful to run tests in parallel on Scala.js, because tests can invoke API calls that are truly asynchronous by calling into external APIs that take advantage of non-JavaScript threads. Thus on Scala.js, ParallelTestExecution allows asynchronous tests to run in parallel, even though they must be started sequentially. This may give you better performance when you are using API calls in your Scala.js tests that are truly asynchronous.

Futures and expected exceptions

If you need to test for expected exceptions in the context of futures, you can use the recoverToSucceededIf and recoverToExceptionIf methods of trait RecoverMethods. Because this trait is mixed into supertrait AsyncTestSuite, both of these methods are available by default in an AsyncFunSuite.

If you just want to ensure that a future fails with a particular exception type, and do not need to inspect the exception further, use recoverToSucceededIf:

recoverToSucceededIf[IllegalStateException] { // Result type: Future[Assertion]
  emptyStackActor ? Peek
}

The recoverToSucceededIf method performs a job similar to assertThrows, except in the context of a future. It transforms a Future of any type into a Future[Assertion] that succeeds only if the original future fails with the specified exception. Here's an example in the REPL:

scala> import org.scalatest.RecoverMethods._
import org.scalatest.RecoverMethods._

scala> import scala.concurrent.Future
import scala.concurrent.Future

scala> import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.ExecutionContext.Implicits.global

scala> recoverToSucceededIf[IllegalStateException] {
     |   Future { throw new IllegalStateException }
     | }
res0: scala.concurrent.Future[org.scalatest.Assertion] = ...

scala> res0.value
res1: Option[scala.util.Try[org.scalatest.Assertion]] = Some(Success(Succeeded))

Otherwise it fails with an error message similar to those given by assertThrows:

scala> recoverToSucceededIf[IllegalStateException] {
     |   Future { throw new RuntimeException }
     | }
res2: scala.concurrent.Future[org.scalatest.Assertion] = ...

scala> res2.value
res3: Option[scala.util.Try[org.scalatest.Assertion]] =
    Some(Failure(org.scalatest.exceptions.TestFailedException: Expected exception
      java.lang.IllegalStateException to be thrown, but java.lang.RuntimeException
      was thrown))

scala> recoverToSucceededIf[IllegalStateException] {
     |   Future { 42 }
     | }
res4: scala.concurrent.Future[org.scalatest.Assertion] = ...

scala> res4.value
res5: Option[scala.util.Try[org.scalatest.Assertion]] =
    Some(Failure(org.scalatest.exceptions.TestFailedException: Expected exception
      java.lang.IllegalStateException to be thrown, but no exception was thrown))

The recoverToExceptionIf method differs from the recoverToSucceededIf in its behavior when the assertion succeeds: recoverToSucceededIf yields a Future[Assertion], whereas recoverToExceptionIf yields a Future[T], where T is the expected exception type.

recoverToExceptionIf[IllegalStateException] { // Result type: Future[IllegalStateException]
  emptyStackActor ? Peek
}

In other words, recoverToExpectionIf is to intercept as recovertToSucceededIf is to assertThrows. The first one allows you to perform further assertions on the expected exception. The second one gives you a result type that will satisfy the type checker at the end of the test body. Here's an example showing recoverToExceptionIf in the REPL:

scala> val futureEx =
     |   recoverToExceptionIf[IllegalStateException] {
     |     Future { throw new IllegalStateException("hello") }
     |   }
futureEx: scala.concurrent.Future[IllegalStateException] = ...

scala> futureEx.value
res6: Option[scala.util.Try[IllegalStateException]] =
    Some(Success(java.lang.IllegalStateException: hello))

scala> futureEx map { ex => assert(ex.getMessage == "world") }
res7: scala.concurrent.Future[org.scalatest.Assertion] = ...

scala> res7.value
res8: Option[scala.util.Try[org.scalatest.Assertion]] =
    Some(Failure(org.scalatest.exceptions.TestFailedException: "[hello]" did not equal "[world]"))

Ignored tests

To support the common use case of temporarily disabling a test, with the good intention of resurrecting the test at a later time, AsyncFunSuite provides registration methods that start with ignore instead of test. Here's an example:

package org.scalatest.examples.asyncfunsuite.ignore

import org.scalatest.AsyncFunSuite
import scala.concurrent.Future

class AddSuite extends AsyncFunSuite {

  def addSoon(addends: Int*): Future[Int] = Future { addends.sum }

  ignore("addSoon will eventually compute a sum of passed Ints") {
    val futureSum: Future[Int] = addSoon(1, 2)
    // You can map assertions onto a Future, then return
    // the resulting Future[Assertion] to ScalaTest:
    futureSum map { sum => assert(sum == 3) }
  }

  def addNow(addends: Int*): Int = addends.sum

  test("addNow will immediately compute a sum of passed Ints") {
    val sum: Int = addNow(1, 2)
    // You can also write synchronous tests. The body
    // must have result type Assertion:
    assert(sum == 3)
  }
}

If you run this version of AddSuite with:

scala> org.scalatest.run(new AddSuite)

It will run only the second test and report that the first test was ignored:

AddSuite:
- addSoon will eventually compute a sum of passed Ints !!! IGNORED !!!
- addNow will immediately compute a sum of passed Ints

If you wish to temporarily ignore an entire suite of tests, you can (on the JVM, not Scala.js) annotate the test class with @Ignore, like this:

package org.scalatest.examples.asyncfunsuite.ignoreall

import org.scalatest.AsyncFunSuite
import scala.concurrent.Future
import org.scalatest.Ignore

@Ignore
class AddSuite extends AsyncFunSuite {

  def addSoon(addends: Int*): Future[Int] = Future { addends.sum }

  test("addSoon will eventually compute a sum of passed Ints") {
    val futureSum: Future[Int] = addSoon(1, 2)
    // You can map assertions onto a Future, then return
    // the resulting Future[Assertion] to ScalaTest:
    futureSum map { sum => assert(sum == 3) }
  }

  def addNow(addends: Int*): Int = addends.sum

  test("addNow will immediately compute a sum of passed Ints") {
    val sum: Int = addNow(1, 2)
    // You can also write synchronous tests. The body
    // must have result type Assertion:
    assert(sum == 3)
  }
}

When you mark a test class with a tag annotation, ScalaTest will mark each test defined in that class with that tag. Thus, marking the AddSuite in the above example with the @Ignore tag annotation means that both tests in the class will be ignored. If you run the above AddSuite in the Scala interpreter, you'll see:

scala> org.scalatest.run(new AddSuite)
AddSuite:
- addSoon will eventually compute a sum of passed Ints !!! IGNORED !!!
- addNow will immediately compute a sum of passed Ints !!! IGNORED !!!

Note that marking a test class as ignored won't prevent it from being discovered by ScalaTest. Ignored classes will be discovered and run, and all their tests will be reported as ignored. This is intended to keep the ignored class visible, to encourage the developers to eventually fix and “un-ignore” it. If you want to prevent a class from being discovered at all (on the JVM, not Scala.js), use the DoNotDiscover annotation instead.

If you want to ignore all tests of a suite on Scala.js, where annotations can't be inspected at runtime, you'll need to change test to ignore at each test site. To make a suite non-discoverable on Scala.js, ensure it does not declare a public no-arg constructor. You can either declare a public constructor that takes one or more arguments, or make the no-arg constructor non-public. Because this technique will also make the suite non-discoverable on the JVM, it is a good approach for suites you want to run (but not be discoverable) on both Scala.js and the JVM.

Informers

One of the parameters to AsyncFunSuite's run method is a Reporter, which will collect and report information about the running suite of tests. Information about suites and tests that were run, whether tests succeeded or failed, and tests that were ignored will be passed to the Reporter as the suite runs. Most often the reporting done by default by AsyncFunSuite's methods will be sufficient, but occasionally you may wish to provide custom information to the Reporter from a test. For this purpose, an Informer that will forward information to the current Reporter is provided via the info parameterless method. You can pass the extra information to the Informer via its apply method. The Informer will then pass the information to the Reporter via an InfoProvided event. Here's an example that shows both a direct use as well as an indirect use through the methods of GivenWhenThen:

package org.scalatest.examples.asyncfunsuite.info

import collection.mutable
import org.scalatest._

class SetSuite extends AsyncFunSuite with GivenWhenThen {

  test("An element can be added to an empty mutable Set") {

    Given("an empty mutable Set")
    val set = mutable.Set.empty[String]

    When("an element is added")
    set += "clarity"

    Then("the Set should have size 1")
    assert(set.size === 1)

    And("the Set should contain the added element")
    assert(set.contains("clarity"))

    info("That's all folks!")
    succeed
  }
}

If you run this AsyncFunSuite from the interpreter, you will see the following output:

scala> org.scalatest.run(new SetSuite)
SetSuite:
- an element can be added to an empty mutable Set
  + Given an empty mutable Set
  + When an element is added
  + Then the Set should have size 1
  + And the Set should contain the added element
  + That's all folks!

Documenters

AsyncFunSuite also provides a markup method that returns a Documenter, which allows you to send to the Reporter text formatted in Markdown syntax. You can pass the extra information to the Documenter via its apply method. The Documenter will then pass the information to the Reporter via an MarkupProvided event.

Here's an example AsyncFunSuite that uses markup:

package org.scalatest.examples.asyncfunsuite.markup

import collection.mutable
import org.scalatest._

class SetSuite extends AsyncFunSuite with GivenWhenThen {

  markup { """

Mutable Set
-----------

A set is a collection that contains no duplicate elements.

To implement a concrete mutable set, you need to provide implementations
of the following methods:

    def contains(elem: A): Boolean
    def iterator: Iterator[A]
    def += (elem: A): this.type
    def -= (elem: A): this.type

If you wish that methods like `take`,
`drop`, `filter` return the same kind of set,
you should also override:

    def empty: This

It is also good idea to override methods `foreach` and
`size` for efficiency.

  """ }

  test("An element can be added to an empty mutable Set") {

    Given("an empty mutable Set")
    val set = mutable.Set.empty[String]

    When("an element is added")
    set += "clarity"

    Then("the Set should have size 1")
    assert(set.size === 1)

    And("the Set should contain the added element")
    assert(set.contains("clarity"))

    markup("This test finished with a **bold** statement!")
    succeed
  }
}

Although all of ScalaTest's built-in reporters will display the markup text in some form, the HTML reporter will format the markup information into HTML. Thus, the main purpose of markup is to add nicely formatted text to HTML reports. Here's what the above SetSpec would look like in the HTML reporter:

Notifiers and alerters

ScalaTest records text passed to info and markup during tests, and sends the recorded text in the recordedEvents field of test completion events like TestSucceeded and TestFailed. This allows string reporters (like the standard out reporter) to show info and markup text after the test name in a color determined by the outcome of the test. For example, if the test fails, string reporters will show the info and markup text in red. If a test succeeds, string reporters will show the info and markup text in green. While this approach helps the readability of reports, it means that you can't use info to get status updates from long running tests.

To get immediate (i.e., non-recorded) notifications from tests, you can use note (a Notifier) and alert (an Alerter). Here's an example showing the differences:

package org.scalatest.examples.asyncfunsuite.note

import collection.mutable
import org.scalatest._

class SetSuite extends AsyncFunSuite {

  test("An element can be added to an empty mutable Set") {

    info("info is recorded")
    markup("markup is *also* recorded")
    note("notes are sent immediately")
    alert("alerts are also sent immediately")

    val set = mutable.Set.empty[String]
    set += "clarity"
    assert(set.size === 1)
    assert(set.contains("clarity"))
  }
}

Because note and alert information is sent immediately, it will appear before the test name in string reporters, and its color will be unrelated to the ultimate outcome of the test: note text will always appear in green, alert text will always appear in yellow. Here's an example:

scala> org.scalatest.run(new SetSpec)
SetSuite:
  + notes are sent immediately
  + alerts are also sent immediately
- An element can be added to an empty mutable Set
  + info is recorded
  + markup is *also* recorded

Another example is slowpoke notifications. If you find a test is taking a long time to complete, but you're not sure which test, you can enable slowpoke notifications. ScalaTest will use an Alerter to fire an event whenever a test has been running longer than a specified amount of time.

In summary, use info and markup for text that should form part of the specification output. Use note and alert to send status notifications. (Because the HTML reporter is intended to produce a readable, printable specification, info and markup text will appear in the HTML report, but note and alert text will not.)

Pending tests

A pending test is one that has been given a name but is not yet implemented. The purpose of pending tests is to facilitate a style of testing in which documentation of behavior is sketched out before tests are written to verify that behavior (and often, before the behavior of the system being tested is itself implemented). Such sketches form a kind of specification of what tests and functionality to implement later.

To support this style of testing, a test can be given a name that specifies one bit of behavior required by the system being tested. At the end of the test, it can call method pending, which will cause it to complete abruptly with TestPendingException.

Because tests in ScalaTest can be designated as pending with TestPendingException, both the test name and any information sent to the reporter when running the test can appear in the report of a test run. (In other words, the code of a pending test is executed just like any other test.) However, because the test completes abruptly with TestPendingException, the test will be reported as pending, to indicate the actual test, and possibly the functionality, has not yet been implemented. Here's an example:

package org.scalatest.examples.asyncfunsuite.pending

import org.scalatest.AsyncFunSuite
import scala.concurrent.Future

class AddSuite extends AsyncFunSuite {

  def addSoon(addends: Int*): Future[Int] = Future { addends.sum }

  test("addSoon will eventually compute a sum of passed Ints") (pending)

  def addNow(addends: Int*): Int = addends.sum

  test("addNow will immediately compute a sum of passed Ints") {
    val sum: Int = addNow(1, 2)
    // You can also write synchronous tests. The body
    // must have result type Assertion:
    assert(sum == 3)
  }
}

(Note: "(pending)" is the body of the test. Thus the test contains just one statement, an invocation of the pending method, which throws TestPendingException.) If you run this version of AddSuite with:

scala> org.scalatest.run(new AddSuite)

It will run both tests, but report that first test is pending. You'll see:

AddSuite:
- addSoon will eventually compute a sum of passed Ints (pending)
- addNow will immediately compute a sum of passed Ints

One difference between an ignored test and a pending one is that an ignored test is intended to be used during significant refactorings of the code under test, when tests break and you don't want to spend the time to fix all of them immediately. You can mark some of those broken tests as ignored temporarily, so that you can focus the red bar on just failing tests you actually want to fix immediately. Later you can go back and fix the ignored tests. In other words, by ignoring some failing tests temporarily, you can more easily notice failed tests that you actually want to fix. By contrast, a pending test is intended to be used before a test and/or the code under test is written. Pending indicates you've decided to write a test for a bit of behavior, but either you haven't written the test yet, or have only written part of it, or perhaps you've written the test but don't want to implement the behavior it tests until after you've implemented a different bit of behavior you realized you need first. Thus ignored tests are designed to facilitate refactoring of existing code whereas pending tests are designed to facilitate the creation of new code.

One other difference between ignored and pending tests is that ignored tests are implemented as a test tag that is excluded by default. Thus an ignored test is never executed. By contrast, a pending test is implemented as a test that throws TestPendingException (which is what calling the pending method does). Thus the body of pending tests are executed up until they throw TestPendingException.

Tagging tests

An AsyncFunSuite's tests may be classified into groups by tagging them with string names. As with any suite, when executing an AsyncFunSuite, groups of tests can optionally be included and/or excluded. To tag an AsyncFunSuite's tests, you pass objects that extend class org.scalatest.Tag to methods that register tests. Class Tag takes one parameter, a string name. If you have created tag annotation interfaces as described in the Tag documentation, then you will probably want to use tag names on your test functions that match. To do so, simply pass the fully qualified names of the tag interfaces to the Tag constructor. For example, if you've defined a tag annotation interface with fully qualified name, com.mycompany.tags.DbTest, then you could create a matching tag for AsyncFunSuites like this:

package org.scalatest.examples.asyncfunsuite.tagging

import org.scalatest.Tag

object DbTest extends Tag("com.mycompany.tags.DbTest")

Given these definitions, you could place AsyncFunSuite tests into groups with tags like this:

import org.scalatest.AsyncFunSuite
import org.scalatest.tagobjects.Slow
import scala.concurrent.Future

class AddSuite extends AsyncFunSuite {

  def addSoon(addends: Int*): Future[Int] = Future { addends.sum }

  test("addSoon will eventually compute a sum of passed Ints", Slow) {
    val futureSum: Future[Int] = addSoon(1, 2)
    // You can map assertions onto a Future, then return
    // the resulting Future[Assertion] to ScalaTest:
    futureSum map { sum => assert(sum == 3) }
  }

  def addNow(addends: Int*): Int = addends.sum

  test("addNow will immediately compute a sum of passed Ints",
      Slow, DbTest) {

    val sum: Int = addNow(1, 2)
    // You can also write synchronous tests. The body
    // must have result type Assertion:
    assert(sum == 3)
  }
}

This code marks both tests with the org.scalatest.tags.Slow tag, and the second test with the com.mycompany.tags.DbTest tag.

The run method takes a Filter, whose constructor takes an optional Set[String] called tagsToInclude and a Set[String] called tagsToExclude. If tagsToInclude is None, all tests will be run except those those belonging to tags listed in the tagsToExclude Set. If tagsToInclude is defined, only tests belonging to tags mentioned in the tagsToInclude set, and not mentioned in tagsToExclude, will be run.

It is recommended, though not required, that you create a corresponding tag annotation when you create a Tag object. A tag annotation (on the JVM, not Scala.js) allows you to tag all the tests of an AsyncFunSuite in one stroke by annotating the class. For more information and examples, see the documentation for class Tag. On Scala.js, to tag all tests of a suite, you'll need to tag each test individually at the test site.

Shared fixtures

A test fixture is composed of the objects and other artifacts (files, sockets, database connections, etc.) tests use to do their work. When multiple tests need to work with the same fixtures, it is important to try and avoid duplicating the fixture code across those tests. The more code duplication you have in your tests, the greater drag the tests will have on refactoring the actual production code.

ScalaTest recommends three techniques to eliminate such code duplication in async styles:

Each technique is geared towards helping you reduce code duplication without introducing instance vars, shared mutable objects, or other dependencies between tests. Eliminating shared mutable state across tests will make your test code easier to reason about and eliminate the need to synchronize access to shared mutable state on the JVM.

The following sections describe these techniques, including explaining the recommended usage for each. But first, here's a table summarizing the options:

Refactor using Scala when different tests need different fixtures.
get-fixture methods The extract method refactor helps you create a fresh instances of mutable fixture objects in each test that needs them, but doesn't help you clean them up when you're done.
loan-fixture methods Factor out dupicate code with the loan pattern when different tests need different fixtures that must be cleaned up afterwards.
Override withFixture when most or all tests need the same fixture.
withFixture(NoArgAsyncTest) The recommended default approach when most or all tests need the same fixture treatment. This general technique allows you, for example, to perform side effects at the beginning and end of all or most tests, transform the outcome of tests, retry tests, make decisions based on test names, tags, or other test data. Use this technique unless:
Different tests need different fixtures (refactor using Scala instead)
An exception in fixture code should abort the suite, not fail the test (use a before-and-after trait instead)
You have objects to pass into tests (override withFixture(OneArgAsyncTest) instead)
withFixture(OneArgAsyncTest) Use when you want to pass the same fixture object or objects as a parameter into all or most tests.
Mix in a before-and-after trait when you want an aborted suite, not a failed test, if the fixture code fails.
BeforeAndAfter Use this boilerplate-buster when you need to perform the same side-effects before and/or after tests, rather than at the beginning or end of tests.
BeforeAndAfterEach Use when you want to stack traits that perform the same side-effects before and/or after tests, rather than at the beginning or end of tests.

Calling get-fixture methods

If you need to create the same mutable fixture objects in multiple tests, and don't need to clean them up after using them, the simplest approach is to write one or more get-fixture methods. A get-fixture method returns a new instance of a needed fixture object (or a holder object containing multiple fixture objects) each time it is called. You can call a get-fixture method at the beginning of each test that needs the fixture, storing the returned object or objects in local variables. Here's an example:

package org.scalatest.examples.asyncfunsuite.getfixture

import org.scalatest.AsyncFunSuite
import collection.mutable.ListBuffer
import scala.concurrent.Future

class ExampleSuite extends AsyncFunSuite {

  def fixture: Future[String] = Future { "ScalaTest is " }

  test("Testing should be easy") {
    val future = fixture
    val result = future map { s => s + "easy!" }
    result map { s =>
      assert(s === "ScalaTest is easy!")
    }
  }

  test("Testing should be fun") {
    val future = fixture
    val result = future map { s => s + "fun!" }
    result map { s =>
      assert(s === "ScalaTest is fun!")
    }
  }
}

If you need to configure fixture objects differently in different tests, you can pass configuration into the get-fixture method. For example, you could pass in an initial value for a fixture object as a parameter to the get-fixture method.

Overriding withFixture(NoArgAsyncTest)

Although the get-fixture method approach takes care of setting up a fixture at the beginning of each test, it doesn't address the problem of cleaning up a fixture at the end of the test. If you just need to perform a side-effect at the beginning or end of a test, and don't need to actually pass any fixture objects into the test, you can override withFixture(NoArgAsyncTest), a method defined in trait AsyncTestSuite, a supertrait of AsyncFunSuite.

Trait AsyncFunSuite's runTest method passes a no-arg async test function to withFixture(NoArgAsyncTest). It is withFixture's responsibility to invoke that test function. The default implementation of withFixture simply invokes the function and returns the result, like this:

// Default implementation in trait AsyncTestSuite
protected def withFixture(test: NoArgAsyncTest): FutureOutcome = {
  test()
}

You can, therefore, override withFixture to perform setup before invoking the test function, and/or perform cleanup after the test completes. The recommended way to ensure cleanup is performed after a test completes is to use the complete-lastly syntax, defined in supertrait CompleteLastly. The complete-lastly syntax will ensure that cleanup will occur whether future-producing code completes abruptly by throwing an exception, or returns normally yielding a future. In the latter case, complete-lastly will register the cleanup code to execute asynchronously when the future completes.

The withFixture method is designed to be stacked, and to enable this, you should always call the super implementation of withFixture, and let it invoke the test function rather than invoking the test function directly. In other words, instead of writing “test()”, you should write “super.withFixture(test)”, like this:

// Your implementation
override def withFixture(test: NoArgAsyncTest) = {

  // Perform setup here

  complete {
    super.withFixture(test) // Invoke the test function
  } lastly {
    // Perform cleanup here
  }
}

If you have no cleanup to perform, you can write withFixture like this instead:

// Your implementation
override def withFixture(test: NoArgAsyncTest) = {

  // Perform setup here

  super.withFixture(test) // Invoke the test function
}

If you want to perform an action only for certain outcomes, you'll need to register code performing that action as a callback on the Future using one of Future's registration methods: onComplete, onSuccess, or onFailure. Note that if a test fails, that will be treated as a scala.util.Success(org.scalatest.Failed). So if you want to perform an action if a test fails, for example, you'd register the callback using onSuccess.

Here's an example in which withFixture(NoArgAsyncTest) is used to take a snapshot of the working directory if a test fails, and send that information to the standard output stream:

package org.scalatest.examples.asyncfunsuite.noargasynctest

import java.io.File
import org.scalatest._
import scala.concurrent.Future

class ExampleSuite extends AsyncFunSuite {

  override def withFixture(test: NoArgAsyncTest) = {

    super.withFixture(test) onFailedThen { _ =>
      val currDir = new File(".")
      val fileNames = currDir.list()
      info("Dir snapshot: " + fileNames.mkString(", "))
    }
  }

  def addSoon(addends: Int*): Future[Int] = Future { addends.sum }

  test("This test should succeed") {
    addSoon(1, 1) map { sum => assert(sum === 2) }
  }

  test("This test should fail") {
    addSoon(1, 1) map { sum => assert(sum === 3) }
  }
}

Running this version of ExampleSuite in the interpreter in a directory with two files, hello.txt and world.txt would give the following output:

scala> org.scalatest.run(new ExampleSuite)
ExampleSuite:
- this test should succeed
Dir snapshot: hello.txt, world.txt
- this test should fail *** FAILED ***
  2 did not equal 3 (:33)

Note that the NoArgAsyncTest passed to withFixture, in addition to an apply method that executes the test, also includes the test name and the config map passed to runTest. Thus you can also use the test name and configuration objects in your withFixture implementation.

Lastly, if you want to transform the outcome in some way in withFixture, you'll need to use either the map or transform methods of Future, like this:

// Your implementation
override def withFixture(test: NoArgAsyncTest) = {

  // Perform setup here

  val futureOutcome = super.withFixture(test) // Invoke the test function

  futureOutcome change { outcome =>
    // transform the outcome into a new outcome here
  }
}

Note that a NoArgAsyncTest's apply method will return a scala.util.Failure only if the test completes abruptly with a "test-fatal" exception (such as OutOfMemoryError) that should cause the suite to abort rather than the test to fail. Thus usually you would use map to transform future outcomes, not transform, so that such test-fatal exceptions pass through unchanged. The suite will abort asynchronously with any exception returned from NoArgAsyncTest's apply method in a scala.util.Failure.

Calling loan-fixture methods

If you need to both pass a fixture object into a test and perform cleanup at the end of the test, you'll need to use the loan pattern. If different tests need different fixtures that require cleanup, you can implement the loan pattern directly by writing loan-fixture methods. A loan-fixture method takes a function whose body forms part or all of a test's code. It creates a fixture, passes it to the test code by invoking the function, then cleans up the fixture after the function returns.

The following example shows three tests that use two fixtures, a database and a file. Both require cleanup after, so each is provided via a loan-fixture method. (In this example, the database is simulated with a StringBuffer.)

package org.scalatest.examples.asyncfunsuite.loanfixture

import java.util.concurrent.ConcurrentHashMap

import scala.concurrent.Future
import scala.concurrent.ExecutionContext

object DbServer { // Simulating a database server
  type Db = StringBuffer
  private final val databases = new ConcurrentHashMap[String, Db]
  def createDb(name: String): Db = {
    val db = new StringBuffer // java.lang.StringBuffer is thread-safe
    databases.put(name, db)
    db
  }
  def removeDb(name: String): Unit = {
    databases.remove(name)
  }
}

// Defining actor messages
sealed abstract class StringOp
case object Clear extends StringOp
case class Append(value: String) extends StringOp
case object GetValue

class StringActor { // Simulating an actor
  private final val sb = new StringBuilder
  def !(op: StringOp): Unit =
    synchronized {
      op match {
        case Append(value) => sb.append(value)
        case Clear => sb.clear()
      }
    }
  def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[String] =
    Future {
      synchronized { sb.toString }
    }
}

import org.scalatest._
import DbServer._
import java.util.UUID.randomUUID

class ExampleSuite extends AsyncFunSuite {

  def withDatabase(testCode: Future[Db] => Future[Assertion]) = {
    val dbName = randomUUID.toString // generate a unique db name
    val futureDb = Future { createDb(dbName) } // create the fixture
    complete {
      val futurePopulatedDb =
        futureDb map { db =>
          db.append("ScalaTest is ") // perform setup
        }
      testCode(futurePopulatedDb) // "loan" the fixture to the test code
    } lastly {
      removeDb(dbName) // ensure the fixture will be cleaned up
    }
  }

  def withActor(testCode: StringActor => Future[Assertion]) = {
    val actor = new StringActor
    complete {
      actor ! Append("ScalaTest is ") // set up the fixture
      testCode(actor) // "loan" the fixture to the test code
    } lastly {
      actor ! Clear // ensure the fixture will be cleaned up
    }
  }

  // This test needs the actor fixture
  test("Testing should be productive") {
    withActor { actor =>
      actor ! Append("productive!")
      val futureString = actor ? GetValue
      futureString map { s =>
        assert(s === "ScalaTest is productive!")
      }
    }
  }

  // This test needs the database fixture
  test("Test code should be readable") {
    withDatabase { futureDb =>
      futureDb map { db =>
        db.append("readable!")
        assert(db.toString === "ScalaTest is readable!")
      }
    }
  }

  // This test needs both the actor and the database
  test("Test code should be clear and concise") {
    withDatabase { futureDb =>
      withActor { actor => // loan-fixture methods compose
        actor ! Append("concise!")
        val futureString = actor ? GetValue
        val futurePair: Future[(Db, String)] =
          futureDb zip futureString
        futurePair map { case (db, s) =>
          db.append("clear!")
          assert(db.toString === "ScalaTest is clear!")
          assert(s === "ScalaTest is concise!")
        }
      }
    }
  }
}

As demonstrated by the last test, loan-fixture methods compose. Not only do loan-fixture methods allow you to give each test the fixture it needs, they allow you to give a test multiple fixtures and clean everything up afterwards.

Also demonstrated in this example is the technique of giving each test its own "fixture sandbox" to play in. When your fixtures involve external side-effects, like creating databases, it is a good idea to give each database a unique name as is done in this example. This keeps tests completely isolated, allowing you to run them in parallel if desired.

Overriding withFixture(OneArgTest)

If all or most tests need the same fixture, you can avoid some of the boilerplate of the loan-fixture method approach by using a fixture.AsyncTestSuite and overriding withFixture(OneArgAsyncTest). Each test in a fixture.AsyncTestSuite takes a fixture as a parameter, allowing you to pass the fixture into the test. You must indicate the type of the fixture parameter by specifying FixtureParam, and implement a withFixture method that takes a OneArgAsyncTest. This withFixture method is responsible for invoking the one-arg async test function, so you can perform fixture set up before invoking and passing the fixture into the test function, and ensure clean up is performed after the test completes.

To enable the stacking of traits that define withFixture(NoArgAsyncTest), it is a good idea to let withFixture(NoArgAsyncTest) invoke the test function instead of invoking the test function directly. To do so, you'll need to convert the OneArgAsyncTest to a NoArgAsyncTest. You can do that by passing the fixture object to the toNoArgAsyncTest method of OneArgAsyncTest. In other words, instead of writing “test(theFixture)”, you'd delegate responsibility for invoking the test function to the withFixture(NoArgAsyncTest) method of the same instance by writing:

withFixture(test.toNoArgAsyncTest(theFixture))

Here's a complete example:

package org.scalatest.examples.asyncfunsuite.oneargasynctest

import org.scalatest._
import java.io._
import scala.concurrent.Future
import scala.concurrent.ExecutionContext

// Defining actor messages
sealed abstract class StringOp
case object Clear extends StringOp
case class Append(value: String) extends StringOp
case object GetValue

class StringActor { // Simulating an actor
  private final val sb = new StringBuilder
  def !(op: StringOp): Unit =
    synchronized {
      op match {
        case Append(value) => sb.append(value)
        case Clear => sb.clear()
      }
    }
  def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[String] =
    Future {
      synchronized { sb.toString }
    }
}

class ExampleSuite extends fixture.AsyncFunSuite {

  type FixtureParam = StringActor

  def withFixture(test: OneArgAsyncTest): FutureOutcome = {

    val actor = new StringActor
    complete {
      actor ! Append("ScalaTest is ") // set up the fixture
      withFixture(test.toNoArgAsyncTest(actor))
    } lastly {
      actor ! Clear // ensure the fixture will be cleaned up
    }
  }

  test("Testing should be easy") { actor =>
    actor ! Append("easy!")
    val futureString = actor ? GetValue
    futureString map { s =>
      assert(s === "ScalaTest is easy!")
    }
  }

  test("Testing should be fun") { actor =>
    actor ! Append("fun!")
    val futureString = actor ? GetValue
    futureString map { s =>
      assert(s === "ScalaTest is fun!")
    }
  }
}

In this example, the tests required one fixture object, a StringActor. If your tests need multiple fixture objects, you can simply define the FixtureParam type to be a tuple containing the objects or, alternatively, a case class containing the objects. For more information on the withFixture(OneArgAsyncTest) technique, see the documentation for fixture.AsyncFunSuite.

Mixing in BeforeAndAfter

In all the shared fixture examples shown so far, the activities of creating, setting up, and cleaning up the fixture objects have been performed during the test. This means that if an exception occurs during any of these activities, it will be reported as a test failure. Sometimes, however, you may want setup to happen before the test starts, and cleanup after the test has completed, so that if an exception occurs during setup or cleanup, the entire suite aborts and no more tests are attempted. The simplest way to accomplish this in ScalaTest is to mix in trait BeforeAndAfter. With this trait you can denote a bit of code to run before each test with before and/or after each test each test with after, like this:

package org.scalatest.examples.asyncfunsuite.beforeandafter

import org.scalatest.AsyncFunSuite
import org.scalatest.BeforeAndAfter
import collection.mutable.ListBuffer
import scala.concurrent.Future
import scala.concurrent.ExecutionContext

// Defining actor messages
sealed abstract class StringOp
case object Clear extends StringOp
case class Append(value: String) extends StringOp
case object GetValue

class StringActor { // Simulating an actor
  private final val sb = new StringBuilder
  def !(op: StringOp): Unit =
    synchronized {
      op match {
        case Append(value) => sb.append(value)
        case Clear => sb.clear()
      }
    }
  def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[String] =
    Future {
      synchronized { sb.toString }
    }
}

class ExampleSuite extends AsyncFunSuite with BeforeAndAfter {

  final val actor = new StringActor

  before {
    actor ! Append("ScalaTest is ") // set up the fixture
  }

  after {
    actor ! Clear // clean up the fixture
  }

  test("testing should be easy") {
    actor ! Append("easy!")
    val futureString = actor ? GetValue
    futureString map { s =>
      assert(s === "ScalaTest is easy!")
    }
  }

  test("testing should be fun") {
    actor ! Append("fun!")
    val futureString = actor ? GetValue
    futureString map { s =>
      assert(s === "ScalaTest is fun!")
    }
  }
}

Note that the only way before and after code can communicate with test code is via some side-effecting mechanism, commonly by reassigning instance vars or by changing the state of mutable objects held from instance vals (as in this example). If using instance vars or mutable objects held from instance vals you wouldn't be able to run tests in parallel in the same instance of the test class (on the JVM, not Scala.js) unless you synchronized access to the shared, mutable state.

Note that on the JVM, if you override ScalaTest's default serial execution context, you will likely need to worry about synchronizing access to shared mutable fixture state, because the execution context may assign different threads to process different Future transformations. Although access to mutable state along the same linear chain of Future transformations need not be synchronized, it can be difficult to spot cases where these constraints are violated. The best approach is to use only immutable objects when transforming Futures. When that's not practical, involve only thread-safe mutable objects, as is done in the above example. On Scala.js, by contrast, you need not worry about thread synchronization, because in effect only one thread exists.

Although BeforeAndAfter provides a minimal-boilerplate way to execute code before and after tests, it isn't designed to enable stackable traits, because the order of execution would be non-obvious. If you want to factor out before and after code that is common to multiple test suites, you should use trait BeforeAndAfterEach instead, as shown later in the next section, composing fixtures by stacking traits.

Composing fixtures by stacking traits

In larger projects, teams often end up with several different fixtures that test classes need in different combinations, and possibly initialized (and cleaned up) in different orders. A good way to accomplish this in ScalaTest is to factor the individual fixtures into traits that can be composed using the stackable trait pattern. This can be done, for example, by placing withFixture methods in several traits, each of which call super.withFixture. Here's an example in which the StringBuilderActor and StringBufferActor fixtures used in the previous examples have been factored out into two stackable fixture traits named Builder and Buffer:

package org.scalatest.examples.asyncfunsuite.composingwithasyncfixture

import org.scalatest._
import org.scalatest.SuiteMixin
import collection.mutable.ListBuffer
import scala.concurrent.Future
import scala.concurrent.ExecutionContext

// Defining actor messages
sealed abstract class StringOp
case object Clear extends StringOp
case class Append(value: String) extends StringOp
case object GetValue

class StringBuilderActor { // Simulating an actor
  private final val sb = new StringBuilder
  def !(op: StringOp): Unit =
    synchronized {
      op match {
        case Append(value) => sb.append(value)
        case Clear => sb.clear()
      }
    }
  def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[String] =
    Future {
      synchronized { sb.toString }
    }
}

class StringBufferActor {
  private final val buf = ListBuffer.empty[String]
  def !(op: StringOp): Unit =
    synchronized {
      op match {
        case Append(value) => buf += value
        case Clear => buf.clear()
      }
    }
  def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[List[String]] =
    Future {
      synchronized { buf.toList }
    }
}

trait Builder extends AsyncTestSuiteMixin { this: AsyncTestSuite =>

  final val builderActor = new StringBuilderActor

  abstract override def withFixture(test: NoArgAsyncTest) = {
    builderActor ! Append("ScalaTest is ")
    complete {
      super.withFixture(test) // To be stackable, must call super.withFixture
    } lastly {
      builderActor ! Clear
    }
  }
}

trait Buffer extends AsyncTestSuiteMixin { this: AsyncTestSuite =>

  final val bufferActor = new StringBufferActor

  abstract override def withFixture(test: NoArgAsyncTest) = {
    complete {
      super.withFixture(test) // To be stackable, must call super.withFixture
    } lastly {
      bufferActor ! Clear
    }
  }
}

class ExampleSuite extends AsyncFunSuite with Builder with Buffer {

  test("Testing should be easy") {
    builderActor ! Append("easy!")
    val futureString = builderActor ? GetValue
    val futureList = bufferActor ? GetValue
    val futurePair: Future[(String, List[String])] = futureString zip futureList
    futurePair map { case (str, lst) =>
      assert(str === "ScalaTest is easy!")
      assert(lst.isEmpty)
      bufferActor ! Append("sweet")
      succeed
    }
  }

  test("Testing should be fun") {
    builderActor ! Append("fun!")
    val futureString = builderActor ? GetValue
    val futureList = bufferActor ? GetValue
    val futurePair: Future[(String, List[String])] = futureString zip futureList
    futurePair map { case (str, lst) =>
      assert(str === "ScalaTest is fun!")
      assert(lst.isEmpty)
      bufferActor ! Append("awesome")
      succeed
    }
  }
}

By mixing in both the Builder and Buffer traits, ExampleSuite gets both fixtures, which will be initialized before each test and cleaned up after. The order the traits are mixed together determines the order of execution. In this case, Builder is “super” to Buffer. If you wanted Buffer to be “super” to Builder, you need only switch the order you mix them together, like this:

class Example2Suite extends AsyncFunSuite with Buffer with Builder

If you only need one fixture you mix in only that trait:

class Example3Suite extends AsyncFunSuite with Builder

Another way to create stackable fixture traits is by extending the BeforeAndAfterEach and/or BeforeAndAfterAll traits. BeforeAndAfterEach has a beforeEach method that will be run before each test (like JUnit's setUp), and an afterEach method that will be run after (like JUnit's tearDown). Similarly, BeforeAndAfterAll has a beforeAll method that will be run before all tests, and an afterAll method that will be run after all tests. Here's what the previously shown example would look like if it were rewritten to use the BeforeAndAfterEach methods instead of withFixture:

package org.scalatest.examples.asyncfunsuite.composingbeforeandaftereach

import org.scalatest._
import org.scalatest.BeforeAndAfterEach
import collection.mutable.ListBuffer
import scala.concurrent.Future
import scala.concurrent.ExecutionContext

// Defining actor messages
sealed abstract class StringOp
case object Clear extends StringOp
case class Append(value: String) extends StringOp
case object GetValue

class StringBuilderActor { // Simulating an actor
  private final val sb = new StringBuilder
  def !(op: StringOp): Unit =
    synchronized {
      op match {
        case Append(value) => sb.append(value)
        case Clear => sb.clear()
      }
    }
  def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[String] =
    Future {
      synchronized { sb.toString }
    }
}

class StringBufferActor {
  private final val buf = ListBuffer.empty[String]
  def !(op: StringOp): Unit =
    synchronized {
      op match {
        case Append(value) => buf += value
        case Clear => buf.clear()
      }
    }
  def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[List[String]] =
    Future {
      synchronized { buf.toList }
    }
}

trait Builder extends BeforeAndAfterEach { this: Suite =>

  final val builderActor = new StringBuilderActor

  override def beforeEach() {
    builderActor ! Append("ScalaTest is ")
    super.beforeEach() // To be stackable, must call super.beforeEach
  }

  override def afterEach() {
    try super.afterEach() // To be stackable, must call super.afterEach
    finally builderActor ! Clear
  }
}

trait Buffer extends BeforeAndAfterEach { this: Suite =>

  final val bufferActor = new StringBufferActor

  override def afterEach() {
    try super.afterEach() // To be stackable, must call super.afterEach
    finally bufferActor ! Clear
  }
}

class ExampleSuite extends AsyncFunSuite with Builder with Buffer {

  test("Testing should be easy") {
    builderActor ! Append("easy!")
    val futureString = builderActor ? GetValue
    val futureList = bufferActor ? GetValue
    val futurePair: Future[(String, List[String])] = futureString zip futureList
    futurePair map { case (str, lst) =>
      assert(str === "ScalaTest is easy!")
      assert(lst.isEmpty)
      bufferActor ! Append("sweet")
      succeed
    }
  }

  test("Testing should be fun") {
    builderActor ! Append("fun!")
    val futureString = builderActor ? GetValue
    val futureList = bufferActor ? GetValue
    val futurePair: Future[(String, List[String])] = futureString zip futureList
    futurePair map { case (str, lst) =>
      assert(str === "ScalaTest is fun!")
      assert(lst.isEmpty)
      bufferActor ! Append("awesome")
      succeed
    }
  }
}

To get the same ordering as withFixture, place your super.beforeEach call at the end of each beforeEach method, and the super.afterEach call at the beginning of each afterEach method, as shown in the previous example. It is a good idea to invoke super.afterEach in a try block and perform cleanup in a finally clause, as shown in the previous example, because this ensures the cleanup code is performed even if super.afterEach throws an exception.

The difference between stacking traits that extend BeforeAndAfterEach versus traits that implement withFixture is that setup and cleanup code happens before and after the test in BeforeAndAfterEach, but at the beginning and end of the test in withFixture. Thus if a withFixture method completes abruptly with an exception, it is considered a failed test. By contrast, if any of the beforeEach or afterEach methods of BeforeAndAfterEach complete abruptly, it is considered an aborted suite, which will result in a SuiteAborted event.

Shared tests

Sometimes you may want to run the same test code on different fixture objects. In other words, you may want to write tests that are "shared" by different fixture objects. To accomplish this in an AsyncFunSuite, you first place shared tests in behavior functions. These behavior functions will be invoked during the construction phase of any AsyncFunSuite that uses them, so that the tests they contain will be registered as tests in that AsyncFunSuite. For example, given this StackActor class:

package org.scalatest.examples.asyncfunsuite.sharedtests

import scala.collection.mutable.ListBuffer
import scala.concurrent.Future
import scala.concurrent.ExecutionContext

// Stack operations
case class Push[T](value: T)
sealed abstract class StackOp
case object Pop extends StackOp
case object Peek extends StackOp
case object Size extends StackOp

// Stack info
case class StackInfo[T](top: Option[T], size: Int, max: Int) {
  require(size >= 0, "size was less than zero")
  require(max >= size, "max was less than size")
  val isFull: Boolean = size == max
  val isEmpty: Boolean = size == 0
}

class StackActor[T](Max: Int, name: String) {

  private final val buf = new ListBuffer[T]

  def !(push: Push[T]): Unit =
    synchronized {
      if (buf.size != Max)
        buf.prepend(push.value)
      else
        throw new IllegalStateException("can't push onto a full stack")
    }

  def ?(op: StackOp)(implicit c: ExecutionContext): Future[StackInfo[T]] =
    synchronized {
      op match {
        case Pop =>
          if (buf.size != 0)
            Future { StackInfo(Some(buf.remove(0)), buf.size, Max) }
          else
            throw new IllegalStateException("can't pop an empty stack")
        case Peek =>
          if (buf.size != 0)
            Future { StackInfo(Some(buf(0)), buf.size, Max) }
          else
            throw new IllegalStateException("can't peek an empty stack")
        case Size =>
          Future { StackInfo(None, buf.size, Max) }
      }
    }

  override def toString: String = name
}

You may want to test the stack represented by the StackActor class in different states: empty, full, with one item, with one item less than capacity, etc. You may find you have several tests that make sense any time the stack is non-empty. Thus you'd ideally want to run those same tests for three stack fixture objects: a full stack, a stack with a one item, and a stack with one item less than capacity. With shared tests, you can factor these tests out into a behavior function, into which you pass the stack fixture to use when running the tests. So in your AsyncFunSuite for StackActor, you'd invoke the behavior function three times, passing in each of the three stack fixtures so that the shared tests are run for all three fixtures.

You can define a behavior function that encapsulates these shared tests inside the AsyncFunSuite that uses them. If they are shared between different AsyncFunSuites, however, you could also define them in a separate trait that is mixed into each AsyncFunSuite that uses them. For example, here the nonEmptyStackActor behavior function (in this case, a behavior method) is defined in a trait along with another method containing shared tests for non-full stacks:

import org.scalatest.AsyncFunSuite

trait AsyncFunSuiteStackBehaviors { this: AsyncFunSuite =>

  def nonEmptyStackActor(createNonEmptyStackActor: => StackActor[Int],
        lastItemAdded: Int, name: String): Unit = {

    test("Size is fired at non-empty stack actor: " + name) {
      val stackActor = createNonEmptyStackActor
      val futureStackInfo = stackActor ? Size
      futureStackInfo map { stackInfo =>
        assert(!stackInfo.isEmpty)
      }
    }

    test("Peek is fired at non-empty stack actor: " + name) {
      val stackActor = createNonEmptyStackActor
      val futurePair: Future[(StackInfo[Int], StackInfo[Int])] =
        for {
          beforePeek <- stackActor ? Size
          afterPeek <- stackActor ? Peek
        } yield (beforePeek, afterPeek)
      futurePair map { case (beforePeek, afterPeek) =>
        assert(afterPeek.top === Some(lastItemAdded))
        assert(afterPeek.size === beforePeek.size)
      }
    }

    test("Pop is fired at non-empty stack actor: " + name) {
      val stackActor = createNonEmptyStackActor
      val futurePair: Future[(StackInfo[Int], StackInfo[Int])] =
        for {
          beforePop <- stackActor ? Size
          afterPop <- stackActor ? Pop
        } yield (beforePop, afterPop)
      futurePair map { case (beforePop, afterPop) =>
        assert(afterPop.top === Some(lastItemAdded))
        assert(afterPop.size === beforePop.size - 1)
      }
    }
  }

  def nonFullStackActor(createNonFullStackActor: => StackActor[Int], name: String): Unit = {

    test("non-full stack actor is not full: " + name) {
      val stackActor = createNonFullStackActor
      val futureStackInfo = stackActor ? Size
      futureStackInfo map { stackInfo =>
        assert(!stackInfo.isFull)
      }
    }

    test("Push is fired at non-full stack actor: " + name) {
      val stackActor = createNonFullStackActor
      val futurePair: Future[(StackInfo[Int], StackInfo[Int])] =
        for {
          beforePush <- stackActor ? Size
          afterPush <- { stackActor ! Push(7); stackActor ? Peek }
        } yield (beforePush, afterPush)
      futurePair map { case (beforePush, afterPush) =>
        assert(afterPush.top === Some(7))
        assert(afterPush.size === beforePush.size + 1)
      }
    }
  }
}

Given these behavior functions, you could invoke them directly, but AsyncFunSuite offers a DSL for the purpose, which looks like this:

testsFor(nonEmptyStackActor(almostEmptyStackActor, LastValuePushed, almostEmptyStackActorName))
testsFor(nonFullStackActor(almostEmptyStackActor, almostEmptyStackActorName))

Here's an example:

class StackSuite extends AsyncFunSuite with AsyncFunSuiteStackBehaviors {

  val Max = 10
  val LastValuePushed = Max - 1

  // Stack fixture creation methods
  val emptyStackActorName = "empty stack actor"
  def emptyStackActor = new StackActor[Int](Max, emptyStackActorName )

  val fullStackActorName = "full stack actor"
  def fullStackActor = {
    val stackActor = new StackActor[Int](Max, fullStackActorName )
    for (i <- 0 until Max)
      stackActor ! Push(i)
    stackActor
  }

  val almostEmptyStackActorName = "almost empty stack actor"
  def almostEmptyStackActor = {
    val stackActor = new StackActor[Int](Max, almostEmptyStackActorName )
    stackActor ! Push(LastValuePushed)
    stackActor
  }

  val almostFullStackActorName = "almost full stack actor"
  def almostFullStackActor = {
    val stackActor = new StackActor[Int](Max, almostFullStackActorName)
    for (i <- 1 to LastValuePushed)
      stackActor ! Push(i)
    stackActor
  }

  test("an empty stack actor is empty") {
    val stackActor = emptyStackActor
    val futureStackInfo = stackActor ? Size
    futureStackInfo map { stackInfo =>
      assert(stackInfo.isEmpty)
    }
  }

  test("Peek is fired at an empty stack actor") {
    recoverToSucceededIf[IllegalStateException] {
      emptyStackActor ? Peek
    }
  }

  test("Pop is fired at an empty stack actor") {
    recoverToSucceededIf[IllegalStateException] {
      emptyStackActor ? Pop
    }
  }

  testsFor(nonEmptyStackActor(almostEmptyStackActor, LastValuePushed, almostEmptyStackActorName))
  testsFor(nonFullStackActor(almostEmptyStackActor, almostEmptyStackActorName))

  testsFor(nonEmptyStackActor(almostFullStackActor, LastValuePushed, almostFullStackActorName))
  testsFor(nonFullStackActor(almostFullStackActor, almostFullStackActorName))

  test("a full stack actor is full") {
    val stackActor = fullStackActor
    val futureStackInfo = stackActor ? Size
    futureStackInfo map { stackInfo =>
      assert(stackInfo.isFull)
    }
  }

  testsFor(nonEmptyStackActor(fullStackActor, LastValuePushed, fullStackActorName))

  test("Push is fired at a full stack actor") {
    val stackActor = fullStackActor
    assertThrows[IllegalStateException] {
      stackActor ! Push(10)
    }
  }
}

If you load these classes into the Scala interpreter (with scalatest's JAR file on the class path), and execute it, you'll see:

scala> org.scalatest.run(new StackSuite)
StackSuite:
StackSuite:
- an empty stack actor is empty
- Peek is fired at an empty stack actor
- Pop is fired at an empty stack actor
- Size is fired at non-empty stack actor: almost empty stack actor
- Peek is fired at non-empty stack actor: almost empty stack actor
- Pop is fired at non-empty stack actor: almost empty stack actor
- non-full stack actor is not full: almost empty stack actor
- Push is fired at non-full stack actor: almost empty stack actor
- Size is fired at non-empty stack actor: almost full stack actor
- Peek is fired at non-empty stack actor: almost full stack actor
- Pop is fired at non-empty stack actor: almost full stack actor
- non-full stack actor is not full: almost full stack actor
- Push is fired at non-full stack actor: almost full stack actor
- a full stack actor is full
- Size is fired at non-empty stack actor: full stack actor
- Peek is fired at non-empty stack actor: full stack actor
- Pop is fired at non-empty stack actor: full stack actor
- Push is fired at a full stack actor

One thing to keep in mind when using shared tests is that in ScalaTest, each test in a suite must have a unique name. If you register the same tests repeatedly in the same suite, one problem you may encounter is an exception at runtime complaining that multiple tests are being registered with the same test name. In a AsyncFunSuite there is no nesting construct analogous to AsyncFunSpec's describe clause. Therefore, you need to do a bit of extra work to ensure that the test names are unique. If a duplicate test name problem shows up in an AsyncFunSuite, you'll need to pass in a prefix or suffix string to add to each test name. You can call toString on the shared fixture object, or pass this string the same way you pass any other data needed by the shared tests. This is the approach taken by the previous AsyncFunSuiteStackBehaviors example.

Given this AsyncFunSuiteStackBehaviors trait, calling it with the stackWithOneItem fixture, like this:

testsFor(nonEmptyStackActor(almostFullStackActor, LastValuePushed, almostFullStackActorName))

yields test names:

Whereas calling it with the stackWithOneItemLessThanCapacity fixture, like this:

testsFor(nonEmptyStack(stackWithOneItemLessThanCapacity, lastValuePushed))

yields different test names:

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  1. AsyncFunSuite
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  6. Informing
  7. AsyncTestRegistration
  8. AsyncTestSuite
  9. CompleteLastly
  10. RecoverMethods
  11. Suite
  12. Serializable
  13. Serializable
  14. Assertions
  15. TripleEquals
  16. TripleEqualsSupport
  17. AnyRef
  18. Any
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Instance Constructors

  1. new AsyncFunSuite()

    Permalink

Type Members

  1. class CheckingEqualizer[L] extends AnyRef

    Permalink
    Definition Classes
    TripleEqualsSupport
  2. class Equalizer[L] extends AnyRef

    Permalink
    Definition Classes
    TripleEqualsSupport
  3. trait NoArgAsyncTest extends () ⇒ FutureOutcome with TestData

    Permalink

    A test function taking no arguments and returning a FutureOutcome.

    A test function taking no arguments and returning a FutureOutcome.

    For more detail and examples, see the relevant section in the documentation for trait AsyncFlatSpec.

    Definition Classes
    AsyncTestSuite
  4. class ResultOfCompleteInvocation[T] extends AnyRef

    Permalink

    Class that provides the lastly method of the complete-lastly syntax.

    Class that provides the lastly method of the complete-lastly syntax.

    Definition Classes
    CompleteLastly

Value Members

  1. final def !=(arg0: Any): Boolean

    Permalink
    Definition Classes
    AnyRef → Any
  2. def !==[T](right: Spread[T]): TripleEqualsInvocationOnSpread[T]

    Permalink
    Definition Classes
    TripleEqualsSupport
  3. def !==(right: Null): TripleEqualsInvocation[Null]

    Permalink
    Definition Classes
    TripleEqualsSupport
  4. def !==[T](right: T): TripleEqualsInvocation[T]

    Permalink
    Definition Classes
    TripleEqualsSupport
  5. final def ##(): Int

    Permalink
    Definition Classes
    AnyRef → Any
  6. final def ==(arg0: Any): Boolean

    Permalink
    Definition Classes
    AnyRef → Any
  7. def ===[T](right: Spread[T]): TripleEqualsInvocationOnSpread[T]

    Permalink
    Definition Classes
    TripleEqualsSupport
  8. def ===(right: Null): TripleEqualsInvocation[Null]

    Permalink
    Definition Classes
    TripleEqualsSupport
  9. def ===[T](right: T): TripleEqualsInvocation[T]

    Permalink
    Definition Classes
    TripleEqualsSupport
  10. def alert: Alerter

    Permalink

    Returns an Alerter that during test execution will forward strings passed to its apply method to the current reporter.

    Returns an Alerter that during test execution will forward strings passed to its apply method to the current reporter. If invoked in a constructor, it will register the passed string for forwarding later during test execution. If invoked while this FunSuite is being executed, such as from inside a test function, it will forward the information to the current reporter immediately. If invoked at any other time, it will print to the standard output. This method can be called safely by any thread.

    Attributes
    protected
    Definition Classes
    AsyncFunSuiteLikeAlerting
  11. final def asInstanceOf[T0]: T0

    Permalink
    Definition Classes
    Any
  12. macro def assert(condition: Boolean, clue: Any)(implicit prettifier: Prettifier, pos: Position): Assertion

    Permalink

    Assert that a boolean condition, described in String message, is true.

    Assert that a boolean condition, described in String message, is true. If the condition is true, this method returns normally. Else, it throws TestFailedException with a helpful error message appended with the String obtained by invoking toString on the specified clue as the exception's detail message.

    This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:

    • assert(a == b, "a good clue")
    • assert(a != b, "a good clue")
    • assert(a === b, "a good clue")
    • assert(a !== b, "a good clue")
    • assert(a > b, "a good clue")
    • assert(a >= b, "a good clue")
    • assert(a < b, "a good clue")
    • assert(a <= b, "a good clue")
    • assert(a startsWith "prefix", "a good clue")
    • assert(a endsWith "postfix", "a good clue")
    • assert(a contains "something", "a good clue")
    • assert(a eq b, "a good clue")
    • assert(a ne b, "a good clue")
    • assert(a > 0 && b > 5, "a good clue")
    • assert(a > 0 || b > 5, "a good clue")
    • assert(a.isEmpty, "a good clue")
    • assert(!a.isEmpty, "a good clue")
    • assert(a.isInstanceOf[String], "a good clue")
    • assert(a.length == 8, "a good clue")
    • assert(a.size == 8, "a good clue")
    • assert(a.exists(_ == 8), "a good clue")

    At this time, any other form of expression will just get a TestFailedException with message saying the given expression was false. In the future, we will enhance this macro to give helpful error messages in more situations. In ScalaTest 2.0, however, this behavior was sufficient to allow the === that returns Boolean to be the default in tests. This makes === consistent between tests and production code.

    condition

    the boolean condition to assert

    clue

    An objects whose toString method returns a message to include in a failure report.

    Definition Classes
    Assertions
    Exceptions thrown

    NullArgumentException if message is null.

    TestFailedException if the condition is false.

  13. macro def assert(condition: Boolean)(implicit prettifier: Prettifier, pos: Position): Assertion

    Permalink

    Assert that a boolean condition is true.

    Assert that a boolean condition is true. If the condition is true, this method returns normally. Else, it throws TestFailedException.

    This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:

    • assert(a == b)
    • assert(a != b)
    • assert(a === b)
    • assert(a !== b)
    • assert(a > b)
    • assert(a >= b)
    • assert(a < b)
    • assert(a <= b)
    • assert(a startsWith "prefix")
    • assert(a endsWith "postfix")
    • assert(a contains "something")
    • assert(a eq b)
    • assert(a ne b)
    • assert(a > 0 && b > 5)
    • assert(a > 0 || b > 5)
    • assert(a.isEmpty)
    • assert(!a.isEmpty)
    • assert(a.isInstanceOf[String])
    • assert(a.length == 8)
    • assert(a.size == 8)
    • assert(a.exists(_ == 8))

    At this time, any other form of expression will get a TestFailedException with message saying the given expression was false. In the future, we will enhance this macro to give helpful error messages in more situations. In ScalaTest 2.0, however, this behavior was sufficient to allow the === that returns Boolean to be the default in tests. This makes === consistent between tests and production code.

    condition

    the boolean condition to assert

    Definition Classes
    Assertions
    Exceptions thrown

    TestFailedException if the condition is false.

  14. macro def assertCompiles(code: String)(implicit pos: Position): Assertion

    Permalink

    Asserts that a given string snippet of code passes both the Scala parser and type checker.

    Asserts that a given string snippet of code passes both the Scala parser and type checker.

    You can use this to make sure a snippet of code compiles:

    assertCompiles("val a: Int = 1")
    

    Although assertCompiles is implemented with a macro that determines at compile time whether the snippet of code represented by the passed string compiles, errors (i.e., snippets of code that do not compile) are reported as test failures at runtime.

    code

    the snippet of code that should compile

    Definition Classes
    Assertions
  15. macro def assertDoesNotCompile(code: String)(implicit pos: Position): Assertion

    Permalink

    Asserts that a given string snippet of code does not pass either the Scala parser or type checker.

    Asserts that a given string snippet of code does not pass either the Scala parser or type checker.

    Often when creating libraries you may wish to ensure that certain arrangements of code that represent potential “user errors” do not compile, so that your library is more error resistant. ScalaTest's Assertions trait includes the following syntax for that purpose:

    assertDoesNotCompile("val a: String = \"a string")
    

    Although assertDoesNotCompile is implemented with a macro that determines at compile time whether the snippet of code represented by the passed string doesn't compile, errors (i.e., snippets of code that do compile) are reported as test failures at runtime.

    Note that the difference between assertTypeError and assertDoesNotCompile is that assertDoesNotCompile will succeed if the given code does not compile for any reason, whereas assertTypeError will only succeed if the given code does not compile because of a type error. If the given code does not compile because of a syntax error, for example, assertDoesNotCompile will return normally but assertTypeError will throw a TestFailedException.

    code

    the snippet of code that should not type check

    Definition Classes
    Assertions
  16. def assertResult(expected: Any)(actual: Any)(implicit prettifier: Prettifier, pos: Position): Assertion

    Permalink

    Assert that the value passed as expected equals the value passed as actual.

    Assert that the value passed as expected equals the value passed as actual. If the actual value equals the expected value (as determined by ==), assertResult returns normally. Else, assertResult throws a TestFailedException whose detail message includes the expected and actual values.

    expected

    the expected value

    actual

    the actual value, which should equal the passed expected value

    Definition Classes
    Assertions
    Exceptions thrown

    TestFailedException if the passed actual value does not equal the passed expected value.

  17. def assertResult(expected: Any, clue: Any)(actual: Any)(implicit prettifier: Prettifier, pos: Position): Assertion

    Permalink

    Assert that the value passed as expected equals the value passed as actual.

    Assert that the value passed as expected equals the value passed as actual. If the actual equals the expected (as determined by ==), assertResult returns normally. Else, if actual is not equal to expected, assertResult throws a TestFailedException whose detail message includes the expected and actual values, as well as the String obtained by invoking toString on the passed clue.

    expected

    the expected value

    clue

    An object whose toString method returns a message to include in a failure report.

    actual

    the actual value, which should equal the passed expected value

    Definition Classes
    Assertions
    Exceptions thrown

    TestFailedException if the passed actual value does not equal the passed expected value.

  18. def assertThrows[T <: AnyRef](f: ⇒ Any)(implicit classTag: ClassTag[T], pos: Position): Assertion

    Permalink

    Ensure that an expected exception is thrown by the passed function value.

    Ensure that an expected exception is thrown by the passed function value. The thrown exception must be an instance of the type specified by the type parameter of this method. This method invokes the passed function. If the function throws an exception that's an instance of the specified type, this method returns Succeeded. Else, whether the passed function returns normally or completes abruptly with a different exception, this method throws TestFailedException.

    Note that the type specified as this method's type parameter may represent any subtype of AnyRef, not just Throwable or one of its subclasses. In Scala, exceptions can be caught based on traits they implement, so it may at times make sense to specify a trait that the intercepted exception's class must mix in. If a class instance is passed for a type that could not possibly be used to catch an exception (such as String, for example), this method will complete abruptly with a TestFailedException.

    Also note that the difference between this method and intercept is that this method does not return the expected exception, so it does not let you perform further assertions on that exception. Instead, this method returns Succeeded, which means it can serve as the last statement in an async- or safe-style suite. It also indicates to the reader of the code that nothing further is expected about the thrown exception other than its type. The recommended usage is to use assertThrows by default, intercept only when you need to inspect the caught exception further.

    f

    the function value that should throw the expected exception

    classTag

    an implicit ClassTag representing the type of the specified type parameter.

    returns

    the Succeeded singleton, if an exception of the expected type is thrown

    Definition Classes
    Assertions
    Exceptions thrown

    TestFailedException if the passed function does not complete abruptly with an exception that's an instance of the specified type.

  19. macro def assertTypeError(code: String)(implicit pos: Position): Assertion

    Permalink

    Asserts that a given string snippet of code does not pass the Scala type checker, failing if the given snippet does not pass the Scala parser.

    Asserts that a given string snippet of code does not pass the Scala type checker, failing if the given snippet does not pass the Scala parser.

    Often when creating libraries you may wish to ensure that certain arrangements of code that represent potential “user errors” do not compile, so that your library is more error resistant. ScalaTest's Assertions trait includes the following syntax for that purpose:

    assertTypeError("val a: String = 1")
    

    Although assertTypeError is implemented with a macro that determines at compile time whether the snippet of code represented by the passed string type checks, errors (i.e., snippets of code that do type check) are reported as test failures at runtime.

    Note that the difference between assertTypeError and assertDoesNotCompile is that assertDoesNotCompile will succeed if the given code does not compile for any reason, whereas assertTypeError will only succeed if the given code does not compile because of a type error. If the given code does not compile because of a syntax error, for example, assertDoesNotCompile will return normally but assertTypeError will throw a TestFailedException.

    code

    the snippet of code that should not type check

    Definition Classes
    Assertions
  20. macro def assume(condition: Boolean, clue: Any)(implicit prettifier: Prettifier, pos: Position): Assertion

    Permalink

    Assume that a boolean condition, described in String message, is true.

    Assume that a boolean condition, described in String message, is true. If the condition is true, this method returns normally. Else, it throws TestCanceledException with a helpful error message appended with String obtained by invoking toString on the specified clue as the exception's detail message.

    This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:

    • assume(a == b, "a good clue")
    • assume(a != b, "a good clue")
    • assume(a === b, "a good clue")
    • assume(a !== b, "a good clue")
    • assume(a > b, "a good clue")
    • assume(a >= b, "a good clue")
    • assume(a < b, "a good clue")
    • assume(a <= b, "a good clue")
    • assume(a startsWith "prefix", "a good clue")
    • assume(a endsWith "postfix", "a good clue")
    • assume(a contains "something", "a good clue")
    • assume(a eq b, "a good clue")
    • assume(a ne b, "a good clue")
    • assume(a > 0 && b > 5, "a good clue")
    • assume(a > 0 || b > 5, "a good clue")
    • assume(a.isEmpty, "a good clue")
    • assume(!a.isEmpty, "a good clue")
    • assume(a.isInstanceOf[String], "a good clue")
    • assume(a.length == 8, "a good clue")
    • assume(a.size == 8, "a good clue")
    • assume(a.exists(_ == 8), "a good clue")

    At this time, any other form of expression will just get a TestCanceledException with message saying the given expression was false. In the future, we will enhance this macro to give helpful error messages in more situations. In ScalaTest 2.0, however, this behavior was sufficient to allow the === that returns Boolean to be the default in tests. This makes === consistent between tests and production code.

    condition

    the boolean condition to assume

    clue

    An objects whose toString method returns a message to include in a failure report.

    Definition Classes
    Assertions
    Exceptions thrown

    NullArgumentException if message is null.

    TestCanceledException if the condition is false.

  21. macro def assume(condition: Boolean)(implicit prettifier: Prettifier, pos: Position): Assertion

    Permalink

    Assume that a boolean condition is true.

    Assume that a boolean condition is true. If the condition is true, this method returns normally. Else, it throws TestCanceledException.

    This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:

    • assume(a == b)
    • assume(a != b)
    • assume(a === b)
    • assume(a !== b)
    • assume(a > b)
    • assume(a >= b)
    • assume(a < b)
    • assume(a <= b)
    • assume(a startsWith "prefix")
    • assume(a endsWith "postfix")
    • assume(a contains "something")
    • assume(a eq b)
    • assume(a ne b)
    • assume(a > 0 && b > 5)
    • assume(a > 0 || b > 5)
    • assume(a.isEmpty)
    • assume(!a.isEmpty)
    • assume(a.isInstanceOf[String])
    • assume(a.length == 8)
    • assume(a.size == 8)
    • assume(a.exists(_ == 8))

    At this time, any other form of expression will just get a TestCanceledException with message saying the given expression was false. In the future, we will enhance this macro to give helpful error messages in more situations. In ScalaTest 2.0, however, this behavior was sufficient to allow the === that returns Boolean to be the default in tests. This makes === consistent between tests and production code.

    condition

    the boolean condition to assume

    Definition Classes
    Assertions
    Exceptions thrown

    TestCanceledException if the condition is false.

  22. def cancel(cause: Throwable)(implicit pos: Position): Nothing

    Permalink

    Throws TestCanceledException, with the passed Throwable cause, to indicate a test failed.

    Throws TestCanceledException, with the passed Throwable cause, to indicate a test failed. The getMessage method of the thrown TestCanceledException will return cause.toString.

    cause

    a Throwable that indicates the cause of the cancellation.

    Definition Classes
    Assertions
    Exceptions thrown

    NullArgumentException if cause is null

  23. def cancel(message: String, cause: Throwable)(implicit pos: Position): Nothing

    Permalink

    Throws TestCanceledException, with the passed String message as the exception's detail message and Throwable cause, to indicate a test failed.

    Throws TestCanceledException, with the passed String message as the exception's detail message and Throwable cause, to indicate a test failed.

    message

    A message describing the failure.

    cause

    A Throwable that indicates the cause of the failure.

    Definition Classes
    Assertions
    Exceptions thrown

    NullArgumentException if message or cause is null

  24. def cancel(message: String)(implicit pos: Position): Nothing

    Permalink

    Throws TestCanceledException, with the passed String message as the exception's detail message, to indicate a test was canceled.

    Throws TestCanceledException, with the passed String message as the exception's detail message, to indicate a test was canceled.

    message

    A message describing the cancellation.

    Definition Classes
    Assertions
    Exceptions thrown

    NullArgumentException if message is null

  25. def cancel()(implicit pos: Position): Nothing

    Permalink

    Throws TestCanceledException to indicate a test was canceled.

    Throws TestCanceledException to indicate a test was canceled.

    Definition Classes
    Assertions
  26. def clone(): AnyRef

    Permalink
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  27. def complete[T](completeBlock: ⇒ T)(implicit futuristic: Futuristic[T]): ResultOfCompleteInvocation[T]

    Permalink

    Registers a block of code that produces any "futuristic" type (any type F for which an implicit Futuristic[F] instance is implicitly available), returning an object that offers a lastly method.

    Registers a block of code that produces any "futuristic" type (any type F for which an implicit Futuristic[F] instance is implicitly available), returning an object that offers a lastly method.

    See the main documentation for trait CompleteLastly for more detail.

    completeBlock

    cleanup code to execute whether the code passed to complete throws an exception or succesfully returns a futuristic value.

    Definition Classes
    CompleteLastly
  28. def conversionCheckedConstraint[A, B](implicit equivalenceOfA: Equivalence[A], cnv: (B) ⇒ A): CanEqual[A, B]

    Permalink
    Definition Classes
    TripleEquals → TripleEqualsSupport
  29. implicit def convertAssertionToFutureAssertion(assertion: compatible.Assertion): Future[compatible.Assertion]

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    Implicitly converts an Assertion to a Future[Assertion].

    Implicitly converts an Assertion to a Future[Assertion].

    This implicit conversion is used to allow synchronous tests to be included along with asynchronous tests in an AsyncTestSuite. It will be

    assertion

    the Assertion to convert

    returns

    a Future[Assertion] that has already completed successfully (containing the Succeeded singleton).

    Definition Classes
    AsyncTestSuite
  30. def convertEquivalenceToAToBConstraint[A, B](equivalenceOfB: Equivalence[B])(implicit ev: <:<[A, B]): CanEqual[A, B]

    Permalink
    Definition Classes
    TripleEquals → TripleEqualsSupport
  31. def convertEquivalenceToAToBConversionConstraint[A, B](equivalenceOfB: Equivalence[B])(implicit ev: (A) ⇒ B): CanEqual[A, B]

    Permalink
    Definition Classes
    TripleEquals → TripleEqualsSupport
  32. def convertEquivalenceToBToAConstraint[A, B](equivalenceOfA: Equivalence[A])(implicit ev: <:<[B, A]): CanEqual[A, B]

    Permalink
    Definition Classes
    TripleEquals → TripleEqualsSupport
  33. def convertEquivalenceToBToAConversionConstraint[A, B](equivalenceOfA: Equivalence[A])(implicit ev: (B) ⇒ A): CanEqual[A, B]

    Permalink
    Definition Classes
    TripleEquals → TripleEqualsSupport
  34. def convertToCheckingEqualizer[T](left: T): CheckingEqualizer[T]

    Permalink
    Definition Classes
    TripleEquals → TripleEqualsSupport
  35. implicit def convertToEqualizer[T](left: T): Equalizer[T]

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    Definition Classes
    TripleEquals → TripleEqualsSupport
  36. def defaultEquality[A]: Equality[A]

    Permalink
    Definition Classes
    TripleEqualsSupport
  37. final def eq(arg0: AnyRef): Boolean

    Permalink
    Definition Classes
    AnyRef
  38. def equals(arg0: Any): Boolean

    Permalink
    Definition Classes
    AnyRef → Any
  39. implicit def executionContext: ExecutionContext

    Permalink
    Definition Classes
    AsyncTestSuite
  40. def expectedTestCount(filter: Filter): Int

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    The total number of tests that are expected to run when this Suite's run method is invoked.

    The total number of tests that are expected to run when this Suite's run method is invoked.

    This trait's implementation of this method returns the sum of:

    • the size of the testNames List, minus the number of tests marked as ignored and any tests that are exluded by the passed Filter
    • the sum of the values obtained by invoking expectedTestCount on every nested Suite contained in nestedSuites
    filter

    a Filter with which to filter tests to count based on their tags

    Definition Classes
    Suite
  41. def fail(cause: Throwable)(implicit pos: Position): Nothing

    Permalink

    Throws TestFailedException, with the passed Throwable cause, to indicate a test failed.

    Throws TestFailedException, with the passed Throwable cause, to indicate a test failed. The getMessage method of the thrown TestFailedException will return cause.toString.

    cause

    a Throwable that indicates the cause of the failure.

    Definition Classes
    Assertions
    Exceptions thrown

    NullArgumentException if cause is null

  42. def fail(message: String, cause: Throwable)(implicit pos: Position): Nothing

    Permalink

    Throws TestFailedException, with the passed String message as the exception's detail message and Throwable cause, to indicate a test failed.

    Throws TestFailedException, with the passed String message as the exception's detail message and Throwable cause, to indicate a test failed.

    message

    A message describing the failure.

    cause

    A Throwable that indicates the cause of the failure.

    Definition Classes
    Assertions
    Exceptions thrown

    NullArgumentException if message or cause is null

  43. def fail(message: String)(implicit pos: Position): Nothing

    Permalink

    Throws TestFailedException, with the passed String message as the exception's detail message, to indicate a test failed.

    Throws TestFailedException, with the passed String message as the exception's detail message, to indicate a test failed.

    message

    A message describing the failure.

    Definition Classes
    Assertions
    Exceptions thrown

    NullArgumentException if message is null

  44. def fail()(implicit pos: Position): Nothing

    Permalink

    Throws TestFailedException to indicate a test failed.

    Throws TestFailedException to indicate a test failed.

    Definition Classes
    Assertions
  45. def finalize(): Unit

    Permalink
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  46. final def getClass(): Class[_]

    Permalink
    Definition Classes
    AnyRef → Any
  47. def hashCode(): Int

    Permalink
    Definition Classes
    AnyRef → Any
  48. def ignore(testName: String, testTags: Tag*)(testFun: ⇒ Future[compatible.Assertion])(implicit pos: Position): Unit

    Permalink

    Register a test to ignore, which has the specified name, optional tags, and function value that takes no arguments.

    Register a test to ignore, which has the specified name, optional tags, and function value that takes no arguments. This method will register the test for later ignoring via an invocation of one of the run methods. This method exists to make it easy to ignore an existing test by changing the call to test to ignore without deleting or commenting out the actual test code. The test will not be run, but a report will be sent that indicates the test was ignored. The passed test name must not have been registered previously on this FunSuite instance.

    testName

    the name of the test

    testTags

    the optional list of tags for this test

    testFun

    the test function

    Attributes
    protected
    Definition Classes
    AsyncFunSuiteLike
    Exceptions thrown

    DuplicateTestNameException if a test with the same name has been registered previously

    NotAllowedException if testName had been registered previously

    TestRegistrationClosedException if invoked after run has been invoked on this suite

  49. def info: Informer

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    Returns an Informer that during test execution will forward strings passed to its apply method to the current reporter.

    Returns an Informer that during test execution will forward strings passed to its apply method to the current reporter. If invoked in a constructor, it will register the passed string for forwarding later during test execution. If invoked from inside a scope, it will forward the information to the current reporter immediately. If invoked from inside a test function, it will record the information and forward it to the current reporter only after the test completed, as recordedEvents of the test completed event, such as TestSucceeded. If invoked at any other time, it will print to the standard output. This method can be called safely by any thread.

    Attributes
    protected
    Definition Classes
    AsyncFunSuiteLikeInforming
  50. def intercept[T <: AnyRef](f: ⇒ Any)(implicit classTag: ClassTag[T], pos: Position): T

    Permalink

    Intercept and return an exception that's expected to be thrown by the passed function value.

    Intercept and return an exception that's expected to be thrown by the passed function value. The thrown exception must be an instance of the type specified by the type parameter of this method. This method invokes the passed function. If the function throws an exception that's an instance of the specified type, this method returns that exception. Else, whether the passed function returns normally or completes abruptly with a different exception, this method throws TestFailedException.

    Note that the type specified as this method's type parameter may represent any subtype of AnyRef, not just Throwable or one of its subclasses. In Scala, exceptions can be caught based on traits they implement, so it may at times make sense to specify a trait that the intercepted exception's class must mix in. If a class instance is passed for a type that could not possibly be used to catch an exception (such as String, for example), this method will complete abruptly with a TestFailedException.

    Also note that the difference between this method and assertThrows is that this method returns the expected exception, so it lets you perform further assertions on that exception. By contrast, the assertThrows method returns Succeeded, which means it can serve as the last statement in an async- or safe-style suite. assertThrows also indicates to the reader of the code that nothing further is expected about the thrown exception other than its type. The recommended usage is to use assertThrows by default, intercept only when you need to inspect the caught exception further.

    f

    the function value that should throw the expected exception

    classTag

    an implicit ClassTag representing the type of the specified type parameter.

    returns

    the intercepted exception, if it is of the expected type

    Definition Classes
    Assertions
    Exceptions thrown

    TestFailedException if the passed function does not complete abruptly with an exception that's an instance of the specified type.

  51. final def isInstanceOf[T0]: Boolean

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    Definition Classes
    Any
  52. def lowPriorityConversionCheckedConstraint[A, B](implicit equivalenceOfB: Equivalence[B], cnv: (A) ⇒ B): CanEqual[A, B]

    Permalink
    Definition Classes
    TripleEquals → TripleEqualsSupport
  53. def lowPriorityTypeCheckedConstraint[A, B](implicit equivalenceOfB: Equivalence[B], ev: <:<[A, B]): CanEqual[A, B]

    Permalink
    Definition Classes
    TripleEquals → TripleEqualsSupport
  54. def markup: Documenter

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    Returns a Documenter that during test execution will forward strings passed to its apply method to the current reporter.

    Returns a Documenter that during test execution will forward strings passed to its apply method to the current reporter. If invoked in a constructor, it will register the passed string for forwarding later during test execution. If invoked from inside a scope, it will forward the information to the current reporter immediately. If invoked from inside a test function, it will record the information and forward it to the current reporter only after the test completed, as recordedEvents of the test completed event, such as TestSucceeded. If invoked at any other time, it will print to the standard output. This method can be called safely by any thread.

    Attributes
    protected
    Definition Classes
    AsyncFunSuiteLikeDocumenting
  55. final def ne(arg0: AnyRef): Boolean

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    Definition Classes
    AnyRef
  56. def nestedSuites: IndexedSeq[Suite]

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    An immutable IndexedSeq of this Suite object's nested Suites.

    An immutable IndexedSeq of this Suite object's nested Suites. If this Suite contains no nested Suites, this method returns an empty IndexedSeq. This trait's implementation of this method returns an empty List.

    Definition Classes
    Suite
  57. def note: Notifier

    Permalink

    Returns a Notifier that during test execution will forward strings passed to its apply method to the current reporter.

    Returns a Notifier that during test execution will forward strings passed to its apply method to the current reporter. If invoked in a constructor, it will register the passed string for forwarding later during test execution. If invoked while this FunSuite is being executed, such as from inside a test function, it will forward the information to the current reporter immediately. If invoked at any other time, it will print to the standard output. This method can be called safely by any thread.

    Attributes
    protected
    Definition Classes
    AsyncFunSuiteLikeNotifying
  58. final def notify(): Unit

    Permalink
    Definition Classes
    AnyRef
  59. final def notifyAll(): Unit

    Permalink
    Definition Classes
    AnyRef
  60. def parallelAsyncTestExecution: Boolean

    Permalink
    Attributes
    protected[org.scalatest]
    Definition Classes
    AsyncTestSuite
  61. def pending: Assertion with PendingStatement

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    Throws TestPendingException to indicate a test is pending.

    Throws TestPendingException to indicate a test is pending.

    A pending test is one that has been given a name but is not yet implemented. The purpose of pending tests is to facilitate a style of testing in which documentation of behavior is sketched out before tests are written to verify that behavior (and often, the before the behavior of the system being tested is itself implemented). Such sketches form a kind of specification of what tests and functionality to implement later.

    To support this style of testing, a test can be given a name that specifies one bit of behavior required by the system being tested. The test can also include some code that sends more information about the behavior to the reporter when the tests run. At the end of the test, it can call method pending, which will cause it to complete abruptly with TestPendingException. Because tests in ScalaTest can be designated as pending with TestPendingException, both the test name and any information sent to the reporter when running the test can appear in the report of a test run. (In other words, the code of a pending test is executed just like any other test.) However, because the test completes abruptly with TestPendingException, the test will be reported as pending, to indicate the actual test, and possibly the functionality it is intended to test, has not yet been implemented.

    Note: This method always completes abruptly with a TestPendingException. Thus it always has a side effect. Methods with side effects are usually invoked with parentheses, as in pending(). This method is defined as a parameterless method, in flagrant contradiction to recommended Scala style, because it forms a kind of DSL for pending tests. It enables tests in suites such as FunSuite or FunSpec to be denoted by placing "(pending)" after the test name, as in:

    test("that style rules are not laws") (pending)
    

    Readers of the code see "pending" in parentheses, which looks like a little note attached to the test name to indicate it is pending. Whereas "(pending()) looks more like a method call, "(pending)" lets readers stay at a higher level, forgetting how it is implemented and just focusing on the intent of the programmer who wrote the code.

    Definition Classes
    Assertions
  62. def pendingUntilFixed(f: ⇒ Unit)(implicit pos: Position): Assertion with PendingStatement

    Permalink

    Execute the passed block of code, and if it completes abruptly, throw TestPendingException, else throw TestFailedException.

    Execute the passed block of code, and if it completes abruptly, throw TestPendingException, else throw TestFailedException.

    This method can be used to temporarily change a failing test into a pending test in such a way that it will automatically turn back into a failing test once the problem originally causing the test to fail has been fixed. At that point, you need only remove the pendingUntilFixed call. In other words, a pendingUntilFixed surrounding a block of code that isn't broken is treated as a test failure. The motivation for this behavior is to encourage people to remove pendingUntilFixed calls when there are no longer needed.

    This method facilitates a style of testing in which tests are written before the code they test. Sometimes you may encounter a test failure that requires more functionality than you want to tackle without writing more tests. In this case you can mark the bit of test code causing the failure with pendingUntilFixed. You can then write more tests and functionality that eventually will get your production code to a point where the original test won't fail anymore. At this point the code block marked with pendingUntilFixed will no longer throw an exception (because the problem has been fixed). This will in turn cause pendingUntilFixed to throw TestFailedException with a detail message explaining you need to go back and remove the pendingUntilFixed call as the problem orginally causing your test code to fail has been fixed.

    f

    a block of code, which if it completes abruptly, should trigger a TestPendingException

    Definition Classes
    Assertions
    Exceptions thrown

    TestPendingException if the passed block of code completes abruptly with an Exception or AssertionError

  63. def recoverToExceptionIf[T <: AnyRef](future: Future[Any])(implicit classTag: ClassTag[T], exCtx: ExecutionContext, pos: Position): Future[T]

    Permalink

    Transforms a future of any type into a Future[T], where T is a given expected exception type, which succeeds if the given future completes with a Failure containing the specified exception type.

    Transforms a future of any type into a Future[T], where T is a given expected exception type, which succeeds if the given future completes with a Failure containing the specified exception type.

    See the main documentation for this trait for more detail and examples.

    future

    A future of any type, which you expect to fail with an exception of the specified type T

    returns

    a Future[T] containing on success the expected exception, or containing on failure a TestFailedException

    Definition Classes
    RecoverMethods
  64. def recoverToSucceededIf[T <: AnyRef](future: Future[Any])(implicit classTag: ClassTag[T], exCtx: ExecutionContext, pos: Position): Future[Assertion]

    Permalink

    Transforms a future of any type into a Future[Assertion] that succeeds if the future completes with a Failure containing the specified exception type.

    Transforms a future of any type into a Future[Assertion] that succeeds if the future completes with a Failure containing the specified exception type.

    See the main documentation for this trait for more detail and examples.

    future

    A future of any type, which you expect to fail with an exception of the specified type T

    returns

    a Future[Assertion] containing on success the Succeeded singleton, or containing on failure a TestFailedException

    Definition Classes
    RecoverMethods
  65. final def registerAsyncTest(testText: String, testTags: Tag*)(testFun: ⇒ Future[compatible.Assertion])(implicit pos: Position): Unit

    Permalink

    Registers a test.

    Registers a test.

    testText

    the test text

    testTags

    the test tags

    testFun

    the test function

    Definition Classes
    AsyncFunSuiteLikeAsyncTestRegistration
  66. final def registerIgnoredAsyncTest(testText: String, testTags: Tag*)(testFun: ⇒ Future[compatible.Assertion])(implicit pos: Position): Unit

    Permalink

    Registers an ignored test.

    Registers an ignored test.

    testText

    the test text

    testTags

    the test tags

    testFun

    the test function

    Definition Classes
    AsyncFunSuiteLikeAsyncTestRegistration
  67. def rerunner: Option[String]

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    The fully qualified class name of the rerunner to rerun this suite.

    The fully qualified class name of the rerunner to rerun this suite. This implementation will look at this.getClass and see if it is either an accessible Suite, or it has a WrapWith annotation. If so, it returns the fully qualified class name wrapped in a Some, or else it returns None.

    Definition Classes
    Suite
  68. def run(testName: Option[String], args: Args): Status

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    Runs this suite of tests.

    Runs this suite of tests.

    If testName is None, this trait's implementation of this method calls these two methods on this object in this order:

    • runNestedSuites
    • runTests

    If testName is defined, then this trait's implementation of this method calls runTests, but does not call runNestedSuites. This behavior is part of the contract of this method. Subclasses that override run must take care not to call runNestedSuites if testName is defined. (The OneInstancePerTest trait depends on this behavior, for example.)

    Subclasses and subtraits that override this run method can implement them without invoking either the runTests or runNestedSuites methods, which are invoked by this trait's implementation of this method. It is recommended, but not required, that subclasses and subtraits that override run in a way that does not invoke runNestedSuites also override runNestedSuites and make it final. Similarly it is recommended, but not required, that subclasses and subtraits that override run in a way that does not invoke runTests also override runTests (and runTest, which this trait's implementation of runTests calls) and make it final. The implementation of these final methods can either invoke the superclass implementation of the method, or throw an UnsupportedOperationException if appropriate. The reason for this recommendation is that ScalaTest includes several traits that override these methods to allow behavior to be mixed into a Suite. For example, trait BeforeAndAfterEach overrides runTestss. In a Suite subclass that no longer invokes runTests from run, the BeforeAndAfterEach trait is not applicable. Mixing it in would have no effect. By making runTests final in such a Suite subtrait, you make the attempt to mix BeforeAndAfterEach into a subclass of your subtrait a compiler error. (It would fail to compile with a complaint that BeforeAndAfterEach is trying to override runTests, which is a final method in your trait.)

    testName

    an optional name of one test to run. If None, all relevant tests should be run. I.e., None acts like a wildcard that means run all relevant tests in this Suite.

    args

    the Args for this run

    returns

    a Status object that indicates when all tests and nested suites started by this method have completed, and whether or not a failure occurred.

    Definition Classes
    AsyncFunSuiteLikeSuite
    Exceptions thrown

    IllegalArgumentException if testName is defined, but no test with the specified test name exists in this Suite

    NullArgumentException if any passed parameter is null.

  69. def runNestedSuites(args: Args): Status

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    Run zero to many of this Suite's nested Suites.

    Run zero to many of this Suite's nested Suites.

    If the passed distributor is None, this trait's implementation of this method invokes run on each nested Suite in the List obtained by invoking nestedSuites. If a nested Suite's run method completes abruptly with an exception, this trait's implementation of this method reports that the Suite aborted and attempts to run the next nested Suite. If the passed distributor is defined, this trait's implementation puts each nested Suite into the Distributor contained in the Some, in the order in which the Suites appear in the List returned by nestedSuites, passing in a new Tracker obtained by invoking nextTracker on the Tracker passed to this method.

    Implementations of this method are responsible for ensuring SuiteStarting events are fired to the Reporter before executing any nested Suite, and either SuiteCompleted or SuiteAborted after executing any nested Suite.

    args

    the Args for this run

    returns

    a Status object that indicates when all nested suites started by this method have completed, and whether or not a failure occurred.

    Attributes
    protected
    Definition Classes
    Suite
    Exceptions thrown

    NullArgumentException if any passed parameter is null.

  70. def runTest(testName: String, args: Args): Status

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    Run a test.

    Run a test. This trait's implementation runs the test registered with the name specified by testName.

    testName

    the name of one test to run.

    args

    the Args for this run

    returns

    a Status object that indicates when the test started by this method has completed, and whether or not it failed .

    Attributes
    protected
    Definition Classes
    AsyncFunSuiteLikeAsyncTestSuiteSuite
    Exceptions thrown

    IllegalArgumentException if testName is defined but a test with that name does not exist on this FunSuite

    NullArgumentException if any of testName, reporter, stopper, or configMap is null.

  71. def runTests(testName: Option[String], args: Args): Status

    Permalink

    Run zero to many of this FunSuite's tests.

    Run zero to many of this FunSuite's tests.

    testName

    an optional name of one test to run. If None, all relevant tests should be run. I.e., None acts like a wildcard that means run all relevant tests in this Suite.

    args

    the Args for this run

    returns

    a Status object that indicates when all tests started by this method have completed, and whether or not a failure occurred.

    Attributes
    protected
    Definition Classes
    AsyncFunSuiteLikeSuite
    Exceptions thrown

    IllegalArgumentException if testName is defined, but no test with the specified test name exists in this Suite

    NullArgumentException if any of the passed parameters is null.

  72. final val styleName: String

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    Suite style name.

    Suite style name.

    Definition Classes
    AsyncFunSuiteLikeSuite
  73. final val succeed: Assertion

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    The Succeeded singleton.

    The Succeeded singleton.

    You can use succeed to solve a type error when an async test does not end in either Future[Assertion] or Assertion. Because Assertion is a type alias for Succeeded.type, putting succeed at the end of a test body (or at the end of a function being used to map the final future of a test body) will solve the type error.

    Definition Classes
    Assertions
  74. def suiteId: String

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    A string ID for this Suite that is intended to be unique among all suites reported during a run.

    A string ID for this Suite that is intended to be unique among all suites reported during a run.

    This trait's implementation of this method returns the fully qualified name of this object's class. Each suite reported during a run will commonly be an instance of a different Suite class, and in such cases, this default implementation of this method will suffice. However, in special cases you may need to override this method to ensure it is unique for each reported suite. For example, if you write a Suite subclass that reads in a file whose name is passed to its constructor and dynamically creates a suite of tests based on the information in that file, you will likely need to override this method in your Suite subclass, perhaps by appending the pathname of the file to the fully qualified class name. That way if you run a suite of tests based on a directory full of these files, you'll have unique suite IDs for each reported suite.

    The suite ID is intended to be unique, because ScalaTest does not enforce that it is unique. If it is not unique, then you may not be able to uniquely identify a particular test of a particular suite. This ability is used, for example, to dynamically tag tests as having failed in the previous run when rerunning only failed tests.

    returns

    this Suite object's ID.

    Definition Classes
    Suite
  75. def suiteName: String

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    A user-friendly suite name for this Suite.

    A user-friendly suite name for this Suite.

    This trait's implementation of this method returns the simple name of this object's class. This trait's implementation of runNestedSuites calls this method to obtain a name for Reports to pass to the suiteStarting, suiteCompleted, and suiteAborted methods of the Reporter.

    returns

    this Suite object's suite name.

    Definition Classes
    Suite
  76. final def synchronized[T0](arg0: ⇒ T0): T0

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    Definition Classes
    AnyRef
  77. def tags: Map[String, Set[String]]

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    A Map whose keys are String names of tagged tests and whose associated values are the Set of tags for the test.

    A Map whose keys are String names of tagged tests and whose associated values are the Set of tags for the test. If this FunSuite contains no tags, this method returns an empty Map.

    This trait's implementation returns tags that were passed as strings contained in Tag objects passed to methods test and ignore.

    In addition, this trait's implementation will also auto-tag tests with class level annotations. For example, if you annotate @Ignore at the class level, all test methods in the class will be auto-annotated with org.scalatest.Ignore.

    Definition Classes
    AsyncFunSuiteLikeSuite
  78. def test(testName: String, testTags: Tag*)(testFun: ⇒ Future[compatible.Assertion])(implicit pos: Position): Unit

    Permalink

    Register a test with the specified name, optional tags, and function value that takes no arguments.

    Register a test with the specified name, optional tags, and function value that takes no arguments. This method will register the test for later execution via an invocation of one of the run methods. The passed test name must not have been registered previously on this FunSuite instance.

    testName

    the name of the test

    testTags

    the optional list of tags for this test

    testFun

    the test function

    Attributes
    protected
    Definition Classes
    AsyncFunSuiteLike
    Exceptions thrown

    DuplicateTestNameException if a test with the same name has been registered previously

    NotAllowedException if testName had been registered previously

    NullArgumentException if testName or any passed test tag is null

    TestRegistrationClosedException if invoked after run has been invoked on this suite

  79. def testDataFor(testName: String, theConfigMap: ConfigMap = ConfigMap.empty): TestData

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    Provides a TestData instance for the passed test name, given the passed config map.

    Provides a TestData instance for the passed test name, given the passed config map.

    This method is used to obtain a TestData instance to pass to withFixture(NoArgTest) and withFixture(OneArgTest) and the beforeEach and afterEach methods of trait BeforeAndAfterEach.

    testName

    the name of the test for which to return a TestData instance

    theConfigMap

    the config map to include in the returned TestData

    returns

    a TestData instance for the specified test, which includes the specified config map

    Definition Classes
    AsyncFunSuiteLikeSuite
  80. def testNames: Set[String]

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    An immutable Set of test names.

    An immutable Set of test names. If this FunSuite contains no tests, this method returns an empty Set.

    This trait's implementation of this method will return a set that contains the names of all registered tests. The set's iterator will return those names in the order in which the tests were registered.

    Definition Classes
    AsyncFunSuiteLikeSuite
  81. def testsFor(unit: Unit): Unit

    Permalink

    Registers shared tests.

    Registers shared tests.

    This method enables the following syntax for shared tests in a FunSuite:

    testsFor(nonEmptyStack(lastValuePushed))
    

    This method just provides syntax sugar intended to make the intent of the code clearer. Because the parameter passed to it is type Unit, the expression will be evaluated before being passed, which is sufficient to register the shared tests. For examples of shared tests, see the Shared tests section in the main documentation for this trait.

    Attributes
    protected
    Definition Classes
    AsyncFunSuiteLike
  82. def toString(): String

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    Returns a user friendly string for this suite, composed of the simple name of the class (possibly simplified further by removing dollar signs if added by the Scala interpeter) and, if this suite contains nested suites, the result of invoking toString on each of the nested suites, separated by commas and surrounded by parentheses.

    Returns a user friendly string for this suite, composed of the simple name of the class (possibly simplified further by removing dollar signs if added by the Scala interpeter) and, if this suite contains nested suites, the result of invoking toString on each of the nested suites, separated by commas and surrounded by parentheses.

    returns

    a user-friendly string for this suite

    Definition Classes
    AsyncFunSuite → AnyRef → Any
  83. def typeCheckedConstraint[A, B](implicit equivalenceOfA: Equivalence[A], ev: <:<[B, A]): CanEqual[A, B]

    Permalink
    Definition Classes
    TripleEquals → TripleEqualsSupport
  84. implicit def unconstrainedEquality[A, B](implicit equalityOfA: Equality[A]): CanEqual[A, B]

    Permalink
    Definition Classes
    TripleEquals → TripleEqualsSupport
  85. final def wait(): Unit

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    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  86. final def wait(arg0: Long, arg1: Int): Unit

    Permalink
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  87. final def wait(arg0: Long): Unit

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    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  88. def withClue[T](clue: Any)(fun: ⇒ T): T

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    Executes the block of code passed as the second parameter, and, if it completes abruptly with a ModifiableMessage exception, prepends the "clue" string passed as the first parameter to the beginning of the detail message of that thrown exception, then rethrows it.

    Executes the block of code passed as the second parameter, and, if it completes abruptly with a ModifiableMessage exception, prepends the "clue" string passed as the first parameter to the beginning of the detail message of that thrown exception, then rethrows it. If clue does not end in a white space character, one space will be added between it and the existing detail message (unless the detail message is not defined).

    This method allows you to add more information about what went wrong that will be reported when a test fails. Here's an example:

    withClue("(Employee's name was: " + employee.name + ")") {
      intercept[IllegalArgumentException] {
        employee.getTask(-1)
      }
    }
    

    If an invocation of intercept completed abruptly with an exception, the resulting message would be something like:

    (Employee's name was Bob Jones) Expected IllegalArgumentException to be thrown, but no exception was thrown
    

    Definition Classes
    Assertions
    Exceptions thrown

    NullArgumentException if the passed clue is null

  89. def withFixture(test: NoArgAsyncTest): FutureOutcome

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    Run the passed test function in the context of a fixture established by this method.

    Run the passed test function in the context of a fixture established by this method.

    This method should set up the fixture needed by the tests of the current suite, invoke the test function, and if needed, register a callback on the resulting FutureOutcome to perform any clean up needed after the test completes. Because the NoArgAsyncTest function passed to this method takes no parameters, preparing the fixture will require side effects, such as reassigning instance vars in this Suite or initializing a globally accessible external database. If you want to avoid reassigning instance vars you can use fixture.AsyncTestSuite.

    This trait's implementation of runTest invokes this method for each test, passing in a NoArgAsyncTest whose apply method will execute the code of the test and returns its result.

    This trait's implementation of this method simply invokes the passed NoArgAsyncTest function.

    test

    the no-arg async test function to run with a fixture

    Definition Classes
    AsyncTestSuite

Deprecated Value Members

  1. def trap[T](f: ⇒ T): Throwable

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    Trap and return any thrown exception that would normally cause a ScalaTest test to fail, or create and return a new RuntimeException indicating no exception is thrown.

    Trap and return any thrown exception that would normally cause a ScalaTest test to fail, or create and return a new RuntimeException indicating no exception is thrown.

    This method is intended to be used in the Scala interpreter to eliminate large stack traces when trying out ScalaTest assertions and matcher expressions. It is not intended to be used in regular test code. If you want to ensure that a bit of code throws an expected exception, use intercept, not trap. Here's an example interpreter session without trap:

    scala> import org.scalatest._
    import org.scalatest._
    
    scala> import Matchers._
    import Matchers._
    
    scala> val x = 12
    a: Int = 12
    
    scala> x shouldEqual 13
    org.scalatest.exceptions.TestFailedException: 12 did not equal 13
       at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:449)
       at org.scalatest.Assertions$.newAssertionFailedException(Assertions.scala:1203)
       at org.scalatest.Assertions$AssertionsHelper.macroAssertTrue(Assertions.scala:417)
       at .<init>(<console>:15)
       at .<clinit>(<console>)
       at .<init>(<console>:7)
       at .<clinit>(<console>)
       at $print(<console>)
       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
       at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
       at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
       at java.lang.reflect.Method.invoke(Method.java:597)
       at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:731)
       at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:980)
       at scala.tools.nsc.interpreter.IMain.loadAndRunReq$1(IMain.scala:570)
       at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:601)
       at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:565)
       at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:745)
       at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:790)
       at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:702)
       at scala.tools.nsc.interpreter.ILoop.processLine$1(ILoop.scala:566)
       at scala.tools.nsc.interpreter.ILoop.innerLoop$1(ILoop.scala:573)
       at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:576)
       at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply$mcZ$sp(ILoop.scala:867)
       at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822)
       at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822)
       at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135)
       at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:822)
       at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:83)
       at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:96)
       at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:105)
       at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)
    

    That's a pretty tall stack trace. Here's what it looks like when you use trap:

    scala> trap { x shouldEqual 13 }
    res1: Throwable = org.scalatest.exceptions.TestFailedException: 12 did not equal 13
    

    Much less clutter. Bear in mind, however, that if no exception is thrown by the passed block of code, the trap method will create a new NormalResult (a subclass of Throwable made for this purpose only) and return that. If the result was the Unit value, it will simply say that no exception was thrown:

    scala> trap { x shouldEqual 12 }
    res2: Throwable = No exception was thrown.
    

    If the passed block of code results in a value other than Unit, the NormalResult's toString will print the value:

    scala> trap { "Dude!" }
    res3: Throwable = No exception was thrown. Instead, result was: "Dude!"
    

    Although you can access the result value from the NormalResult, its type is Any and therefore not very convenient to use. It is not intended that trap be used in test code. The sole intended use case for trap is decluttering Scala interpreter sessions by eliminating stack traces when executing assertion and matcher expressions.

    Definition Classes
    Assertions
    Annotations
    @deprecated
    Deprecated

    The trap method is no longer needed for demos in the REPL, which now abreviates stack traces, and will be removed in a future version of ScalaTest

Inherited from AsyncFunSuiteLike

Inherited from Documenting

Inherited from Alerting

Inherited from Notifying

Inherited from Informing

Inherited from AsyncTestRegistration

Inherited from AsyncTestSuite

Inherited from CompleteLastly

Inherited from RecoverMethods

Inherited from Suite

Inherited from Serializable

Inherited from Serializable

Inherited from Assertions

Inherited from TripleEquals

Inherited from TripleEqualsSupport

Inherited from AnyRef

Inherited from Any

Ungrouped