PartialFunctionValues

Trait that provides an implicit conversion that adds a valueAt method to PartialFunction, which will return the value (result) of the function applied to the argument passed to valueAt, or throw TestFailedException if the partial function is not defined at the argument.

This construct allows you to express in one statement that a partial function should be defined for a particular input, and that its result value should meet some expectation. Here's an example:

pf.valueAt("IV") should equal (4)

Or, using an assertion instead of a matcher expression:

assert(pf.valueAt("IV") === 4)

Were you to simply invoke apply on the PartialFunction, passing in an input value, if the partial function wasn't defined at that input, it would throw some exception, but likely not one that provides a stack depth:

// Note: a Map[K, V] is a PartialFunction[K, V]
val pf: PartialFunction[String, Int] = Map("I" -> 1, "II" -> 2, "III" -> 3, "IV" -> 4)

pf("V") should equal (5) // pf("V") throws NoSuchElementException

The NoSuchElementException thrown in this situation would cause the test to fail, but without providing a stack depth pointing to the failing line of test code. This stack depth, provided by TestFailedException (and a few other ScalaTest exceptions), makes it quicker for users to navigate to the cause of the failure. Without PartialFunctionValues, to get a stack depth exception you would need to make two statements, like this:

val pf: PartialFunction[String, Int] = Map("I" -> 1, "II" -> 2, "III" -> 3, "IV" -> 4)

pf.isDefinedAt("V") should be (true) // throws TestFailedException
pf("V") should equal (5)

The PartialFunctionValues trait allows you to state that more concisely:

val pf: PartialFunction[String, Int] = Map("I" -> 1, "II" -> 2, "III" -> 3, "IV" -> 4)

pf.valueAt("V") should equal (5) // pf.valueAt("V") throws TestFailedException

Source: PartialFunctionValues.scala

Linear Supertypes

AnyRef, Any

Known Subclasses

PartialFunctionValues

Type Members

class Valuable[A, B] extends AnyRef

Wrapper class that adds a valueAt method to PartialFunction, allowing you to make statements like:
Wrapper class that adds a valueAt method to PartialFunction, allowing you to make statements like:
```
pf.valueAt("VI") should equal (6)
```

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( ... )
implicit def convertPartialFunctionToValuable[A, B](pf: PartialFunction[A, B])(implicit pos: Position): Valuable[A, B]

Implicit conversion that adds a valueAt method to PartialFunction.
Implicit conversion that adds a valueAt method to PartialFunction.
pf
the PartialFunction on which to add the valueAt method
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
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 PartialFunctionValues | package scalatest

trait PartialFunctionValues extends AnyRef

Type Members

class Valuable[A, B] extends AnyRef

Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

def clone(): AnyRef

implicit def convertPartialFunctionToValuable[A, B](pf: PartialFunction[A, B])(implicit pos: Position): Valuable[A, B]

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

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