org.scalactic

Catcher

class Catcher extends AnyRef

Convenience class for extractors that match and return Throwables based on a type and Boolean condition.

Class Catcher was motivated by the need to catch and handle exceptions based on more than just the exception's type as a strategy for dealing with "flickering" tests—tests that usually pass, but occasionally fail. The best strategy for dealing with flickers is to fix the test such that they stop flickering, but sometimes that is not practical. In such cases allowing the test to continue flickering can distract the team by requiring them to spend time inspecting failures to determine whether or not they are flickers or real failures that need attention. Worse, with enough flickers, team members can stop checking all failures and not notice real ones.

One strategy for dealing with flickers you can't practically fix is to catch exceptions that are causing individual flickers and cancel the test when you detect them. Often this means you will need to insert a catch clause in a particular spot, or a pattern match if in a withFixture, looking for a particular exception with a particular message or other identifying attribute. If the same problem is causing flickers in many places, it is handy to create an extractor to detect the problem. This Catcher class provides a factory method that takes a partial function from Throwable to Boolean and produces such an extractor. Here's an example:

val InternalServerError =
  Catcher { case e: DBAccessException =>
    e.getMessage == "500:Internal Server Error"
  }

Using this Catcher in a ScalaTest withFixture method would look like:

override def withFixture(test: NoArgTest) = {
  super.withFixture(test) match {
     case Failed(InternalServerError(ex)) =>
       Canceled("Canceled because likely a flicker caused by intermittently flaky DB", ex)
     case other => other
  }
}

Source
Catcher.scala
Linear Supertypes
AnyRef, Any
Ordering
  1. Alphabetic
  2. By inheritance
Inherited
  1. Catcher
  2. AnyRef
  3. Any
  1. Hide All
  2. Show all
Learn more about member selection
Visibility
  1. Public
  2. All

Instance Constructors

  1. new Catcher(partial: PartialFunction[Throwable, Boolean])

    partial

    the partial function that is used by this extractor to determine matches

Value Members

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

    Definition Classes
    AnyRef → Any

  2. final def ##(): Int

    Definition Classes
    AnyRef → Any

  3. final def ==(arg0: Any): Boolean

    Definition Classes
    AnyRef → Any

  4. final def asInstanceOf[T0]: T0

    Definition Classes
    Any

  5. def clone(): AnyRef

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

  6. final def eq(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef

  7. def equals(arg0: Any): Boolean

    Definition Classes
    AnyRef → Any

  8. def finalize(): Unit

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )

  9. final def getClass(): Class[_]

    Definition Classes
    AnyRef → Any

  10. def hashCode(): Int

    Definition Classes
    AnyRef → Any

  11. final def isInstanceOf[T0]: Boolean

    Definition Classes
    Any

  12. final def ne(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef

  13. final def notify(): Unit

    Definition Classes
    AnyRef

  14. final def notifyAll(): Unit

    Definition Classes
    AnyRef

  15. final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
    AnyRef

  16. def toString(): String

    Definition Classes
    AnyRef → Any

  17. def unapply(exception: Throwable): Option[Throwable]

    Extractor for Throwable that determines matches using on the partial function passed to the constructor.

    Extractor for Throwable that determines matches using on the partial function passed to the constructor.

    exception

    the exception on which to match

  18. final def wait(): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

  19. final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

  20. final def wait(arg0: Long): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

Inherited from AnyRef

Inherited from Any

Ungrouped