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  ScalaTest's main traits, classes, and other members, including members supporting ScalaTest's DSL for the Scala interpreter.

  ScalaTest's main traits, classes, and other members, including members supporting ScalaTest's DSL for the Scala interpreter.

  Definition Classes

  org

•  trait AsyncTestSuite extends Suite with RecoverMethods with CompleteLastly

  The base trait of ScalaTest's asynchronous testing styles, which defines a withFixture lifecycle method that accepts as its parameter a test function that returns a FutureOutcome.

  The base trait of ScalaTest's asynchronous testing styles, which defines a withFixture lifecycle method that accepts as its parameter a test function that returns a FutureOutcome.

  The withFixture method add by this trait has the following signature and implementation:

  def withFixture(test: NoArgAsyncTest): FutureOutcome = {
    test()
  }
  

  This trait enables testing of asynchronous code without blocking. Instead of returning Outcome like TestSuite's withFixture, this trait's withFixture method returns a FutureOutcome. Similarly, the apply method of test function interface, NoArgAsyncTest, returns FutureOutcome:

  // In trait NoArgAsyncTest:
  def apply(): FutureOutcome
  

  The withFixture method supports async testing, because when the test function returns, the test body has not necessarily finished execution.

  The recommended way to ensure cleanup is performed after a test body finishes execution is to use a complete-lastly clause, syntax that is defined in trait CompleteLastly, which this trait extends. Using cleanup-lastly will ensure that cleanup will occur whether FutureOutcome-producing code completes abruptly by throwing an exception, or returns normally yielding a FutureOutcome. In the latter case, complete-lastly will register the cleanup code to execute asynchronously when the FutureOutcome 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)”. Thus, the recommended structure of a withFixture implementation that performs cleanup looks 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
  }
  

  The test function and withFixture method returns a FutureOutcome, a ScalaTest class that wraps a Scala Future[Outcome] and offers methods more specific to asynchronous test outcomes. In a Scala Future, any exception results in a scala.util.Failure. In a FutureOutcome, a thrown TestPendingException always results in a Pending, a thrown TestCanceledException always results in a Canceled, and any other exception, so long as it isn't suite-aborting, results in a Failed. This is true of the asynchronous test code itself that's represented by the FutureOutcome and any transformation or callback registered on the FutureOutcome in withFixture.

  If you want to perform an action only for certain outcomes, you'll need to register code performing that action on the FutureOutcome using one of FutureOutcome's callback registration methods:

  • onSucceededThen - executed if the Outcome is a Succeeded.
  • onFailedThen - executed if the Outcome is a Failed.
  • onCanceledThen - executed if the Outcome is a Canceled.
  • onPendingThen - executed if the Outcome is a Pending.
  • onOutcomeThen - executed on any Outcome (i.e., no suite-aborting exception is thrown).
  • onAbortedThen - executed if a suite-aborting exception is thrown.
  • onCompletedThen - executed whether the result is an Outcome or a thrown suite-aborting exception.

  For example, if you want to perform an action if a test fails, you'd register the callback using onFailedThen, like this:

  // Your implementation
  override def withFixture(test: NoArgAsyncTest) = {
  
    // Perform setup here
  
    val futureOutcome = super.withFixture(test) // Invoke the test function
  
    futureOutcome onFailedThen { ex =>
      // perform action that you want to occur
      // only if a test fails here
    }
  }
  

  Note that all callback registration methods, such as onFailedThen used in the previous example, return a new FutureOutcome that won't complete until the the original FutureOutcome and the callback has completed. If the callback throws an exception, the resulting FutureOutcome will represent that exception. For example, if a FutureOutcome results in Failed, but a callback registered on that FutureOutcome with onFailedThen throws TestPendingException, the result of the FutureOutcome returned by onFailedThen will be Pending.

  Lastly, if you want to change the outcome in some way in withFixture, you'll need to use the change method of FutureOutcome, 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
    }
  }
  

  Definition Classes

  scalatest

• CheckingEqualizer
• Equalizer
• NoArgAsyncTest
• ResultOfCompleteInvocation

org.scalatest.AsyncTestSuite

NoArgAsyncTest