Catcher

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

Instance Constructors

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

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

Value Members

final def !=(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def ##(): Int

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

Definition Classes
AnyRef → Any
final def asInstanceOf[T0]: T0

Definition Classes
Any
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( ... )
final def eq(arg0: AnyRef): Boolean

Definition Classes
AnyRef
def equals(arg0: Any): Boolean

Definition Classes
AnyRef → Any
def finalize(): Unit

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

Definition Classes
AnyRef → Any
def hashCode(): Int

Definition Classes
AnyRef → Any
final def isInstanceOf[T0]: Boolean

Definition Classes
Any
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
AnyRef
final def notifyAll(): Unit

Definition Classes
AnyRef
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
def toString(): String

Definition Classes
AnyRef → Any
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
final def wait(): Unit

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

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

Definition Classes
AnyRef
Annotations
@throws( ... )

Related Docs: object Catcher | package scalactic

class Catcher extends AnyRef

Instance Constructors

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

Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

def clone(): AnyRef

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def finalize(): Unit

final def getClass(): Class[_]

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

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

def toString(): String

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

final def wait(): Unit

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

final def wait(arg0: Long): Unit

Inherited from AnyRef

Inherited from Any

Ungrouped