org.scalatest.matchers

MatchResult

case class MatchResult ( matches : Boolean , failureMessage : String , negatedFailureMessage : String , midSentenceFailureMessage : String , midSentenceNegatedFailureMessage : String ) extends Product with Serializable

The result of a match operation, such as one performed by a Matcher or BeMatcher, which contains one field that indicates whether the match succeeded and four fields that provide failure messages to report under different circumstances.

A MatchResult's matches field indicates whether a match succeeded. If it succeeded, matches will be true. The other four fields contain failure message strings, one of which will be presented to the user in case of a match failure. If a match succeeds, none of these strings will be used, because no failure message will be reported (i.e., because there was no failure to report). If a match fails (matches is false), the failureMessage (or midSentenceFailure—more on that below) will be reported to help the user understand what went wrong.

Understanding negatedFailureMessage

The negatedFailureMessage exists so that it can become the failureMessage if the matcher is inverted, which happens, for instance, if it is passed to not. Here's an example:

val equalSeven = equal (7)
val notEqualSeven = not (equalSeven)

The Matcher[Int] that results from passing 7 to equal, which is assigned to the equalSeven variable, will compare Ints passed to its apply method with 7. If 7 is passed, the equalSeven match will succeed. If anything other than 7 is passed, it will fail. By contrast, the notEqualSeven matcher, which results from passing equalSeven to not, does just the opposite. If 7 is passed, the notEqualSeven match will fail. If anything other than 7 is passed, it will succeed.

For example, if 8 is passed, equalSeven's MatchResult will contain:

           expression: equalSeven(8)
              matches: false
       failureMessage: 8 did not equal 7
negatedFailureMessage: 8 equaled 7

Although the negatedFailureMessage is nonsensical, it will not be reported to the user. Only the failureMessage, which does actually explain what caused the failure, will be reported by the user. If you pass 8 to notEqualSeven's apply method, by contrast, the failureMessage and negatedFailureMessage will be:

           expression: notEqualSeven(8)
              matches: true
       failureMessage: 8 equaled 7
negatedFailureMessage: 8 did not equal 7

Note that the messages are swapped from the equalSeven messages. This swapping was effectively performed by the not matcher, which in addition to swapping the failureMessage and negatedFailureMessage, also inverted the matches value. Thus when you pass the same value to both equalSeven and notEqualSeven the matches field of one MatchResult will be true and the other false. Because the matches field of the MatchResult returned by notEqualSeven(8) is true, the nonsensical failureMessage, "8 equaled 7", will not be reported to the user.

If 7 is passed, by contrast, the failureMessage and negatedFailureMessage of equalSeven will be:

           expression: equalSeven(7)
              matches: true
       failureMessage: 7 did not equal 7
negatedFailureMessage: 7 equaled 7

In this case equalSeven's failureMessage is nonsensical, but because the match succeeded, the nonsensical message will not be reported to the user. If you pass 7 to notEqualSeven's apply method, you'll get:

           expression: notEqualSeven(7)
              matches: false
       failureMessage: 7 equaled 7
negatedFailureMessage: 7 did not equal 7

Again the messages are swapped from the equalSeven messages, but this time, the failureMessage makes sense and explains what went wrong: the notEqualSeven match failed because the number passed did in fact equal 7. Since the match failed, this failure message, "7 equaled 7", will be reported to the user.

Understanding the "midSentence" messages

When a ScalaTest matcher expression that involves and or or fails, the failure message that results is composed from the failure messages of the left and right matcher operatnds to and or or. For example:

8 should (equal (7) or equal (9))

This above expression would fail with the following failure message reported to the user:

8 did not equal 7, and 8 did not equal 9

This works fine, but what if the failure messages being combined begin with a capital letter, such as:

The name property did not equal "Ricky"

A combination of two such failure messages might result in an abomination of English punctuation, such as:

The name property did not equal "Ricky", and The name property did not equal "Bobby"

Because ScalaTest is an internationalized application, taking all of its strings from a property file enabling it to be localized, it isn't a good idea to force the first character to lower case. Besides, it might actually represent a String value which should stay upper case. The midSentenceFailureMessage exists for this situation. If the failure message is used at the beginning of the sentence, failureMessage will be used. But if it appears mid-sentence, or at the end of the sentence, midSentenceFailureMessage will be used. Given these failure message strings:

           failureMessage: The name property did not equal "Bobby"
midSentenceFailureMessage: the name property did not equal "Bobby"

The resulting failure of the or expression involving to matchers would make any English teacher proud:

The name property did not equal "Ricky", and the name property did not equal "Bobby"

The result of a match operation, such as one performed by a Matcher or BeMatcher, which contains one field that indicates whether the match succeeded and four fields that provide failure messages to report under different circumstances.

A MatchResult's matches field indicates whether a match succeeded. If it succeeded, matches will be true. The other four fields contain failure message strings, one of which will be presented to the user in case of a match failure. If a match succeeds, none of these strings will be used, because no failure message will be reported (i.e., because there was no failure to report). If a match fails (matches is false), the failureMessage (or midSentenceFailure—more on that below) will be reported to help the user understand what went wrong.

Understanding negatedFailureMessage

The negatedFailureMessage exists so that it can become the failureMessage if the matcher is inverted, which happens, for instance, if it is passed to not. Here's an example:

val equalSeven = equal (7)
val notEqualSeven = not (equalSeven)

The Matcher[Int] that results from passing 7 to equal, which is assigned to the equalSeven variable, will compare Ints passed to its apply method with 7. If 7 is passed, the equalSeven match will succeed. If anything other than 7 is passed, it will fail. By contrast, the notEqualSeven matcher, which results from passing equalSeven to not, does just the opposite. If 7 is passed, the notEqualSeven match will fail. If anything other than 7 is passed, it will succeed.

For example, if 8 is passed, equalSeven's MatchResult will contain:

           expression: equalSeven(8)
              matches: false
       failureMessage: 8 did not equal 7
negatedFailureMessage: 8 equaled 7

Although the negatedFailureMessage is nonsensical, it will not be reported to the user. Only the failureMessage, which does actually explain what caused the failure, will be reported by the user. If you pass 8 to notEqualSeven's apply method, by contrast, the failureMessage and negatedFailureMessage will be:

           expression: notEqualSeven(8)
              matches: true
       failureMessage: 8 equaled 7
negatedFailureMessage: 8 did not equal 7

Note that the messages are swapped from the equalSeven messages. This swapping was effectively performed by the not matcher, which in addition to swapping the failureMessage and negatedFailureMessage, also inverted the matches value. Thus when you pass the same value to both equalSeven and notEqualSeven the matches field of one MatchResult will be true and the other false. Because the matches field of the MatchResult returned by notEqualSeven(8) is true, the nonsensical failureMessage, "8 equaled 7", will not be reported to the user.

If 7 is passed, by contrast, the failureMessage and negatedFailureMessage of equalSeven will be:

           expression: equalSeven(7)
              matches: true
       failureMessage: 7 did not equal 7
negatedFailureMessage: 7 equaled 7

In this case equalSeven's failureMessage is nonsensical, but because the match succeeded, the nonsensical message will not be reported to the user. If you pass 7 to notEqualSeven's apply method, you'll get:

           expression: notEqualSeven(7)
              matches: false
       failureMessage: 7 equaled 7
negatedFailureMessage: 7 did not equal 7

Again the messages are swapped from the equalSeven messages, but this time, the failureMessage makes sense and explains what went wrong: the notEqualSeven match failed because the number passed did in fact equal 7. Since the match failed, this failure message, "7 equaled 7", will be reported to the user.

Understanding the "midSentence" messages

When a ScalaTest matcher expression that involves and or or fails, the failure message that results is composed from the failure messages of the left and right matcher operatnds to and or or. For example:

8 should (equal (7) or equal (9))

This above expression would fail with the following failure message reported to the user:

8 did not equal 7, and 8 did not equal 9

This works fine, but what if the failure messages being combined begin with a capital letter, such as:

The name property did not equal "Ricky"

A combination of two such failure messages might result in an abomination of English punctuation, such as:

The name property did not equal "Ricky", and The name property did not equal "Bobby"

Because ScalaTest is an internationalized application, taking all of its strings from a property file enabling it to be localized, it isn't a good idea to force the first character to lower case. Besides, it might actually represent a String value which should stay upper case. The midSentenceFailureMessage exists for this situation. If the failure message is used at the beginning of the sentence, failureMessage will be used. But if it appears mid-sentence, or at the end of the sentence, midSentenceFailureMessage will be used. Given these failure message strings:

           failureMessage: The name property did not equal "Bobby"
midSentenceFailureMessage: the name property did not equal "Bobby"

The resulting failure of the or expression involving to matchers would make any English teacher proud:

The name property did not equal "Ricky", and the name property did not equal "Bobby"

matches

indicates whether or not the matcher matched

failureMessage

a failure message to report if a match fails

negatedFailureMessage

a message with a meaning opposite to that of the failure message

midSentenceFailureMessage

a failure message suitable for appearing mid-sentence

midSentenceNegatedFailureMessage

a negated failure message suitable for appearing mid-sentence

attributes: final
go to: companion
linear super types: Serializable, Serializable, Product, Equals, AnyRef, Any
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Instance constructors

  1. new MatchResult ( matches : Boolean , failureMessage : String , negatedFailureMessage : String )

    Constructs a new MatchResult with passed matches, failureMessage, and negativeFailureMessage fields. The midSentenceFailureMessage will return the same string as failureMessage, and the midSentenceNegatedFailureMessage will return the same string as negatedFailureMessage.

    Constructs a new MatchResult with passed matches, failureMessage, and negativeFailureMessage fields. The midSentenceFailureMessage will return the same string as failureMessage, and the midSentenceNegatedFailureMessage will return the same string as negatedFailureMessage.

    matches

    indicates whether or not the matcher matched

    failureMessage

    a failure message to report if a match fails

    negatedFailureMessage

    a message with a meaning opposite to that of the failure message

  2. new MatchResult ( matches : Boolean , failureMessage : String , negatedFailureMessage : String , midSentenceFailureMessage : String , midSentenceNegatedFailureMessage : String )

    matches

    indicates whether or not the matcher matched

    failureMessage

    a failure message to report if a match fails

    negatedFailureMessage

    a message with a meaning opposite to that of the failure message

    midSentenceFailureMessage

    a failure message suitable for appearing mid-sentence

    midSentenceNegatedFailureMessage

    a negated failure message suitable for appearing mid-sentence

Value Members

  1. def != ( arg0 : AnyRef ) : Boolean

    attributes: final
    definition classes: AnyRef

  2. def != ( arg0 : Any ) : Boolean

    o != arg0 is the same as !(o == (arg0)).

    o != arg0 is the same as !(o == (arg0)).

    arg0

    the object to compare against this object for dis-equality.

    returns

    false if the receiver object is equivalent to the argument; true otherwise.

    attributes: final
    definition classes: Any

  3. def ## () : Int

    attributes: final
    definition classes: AnyRef → Any

  4. def $asInstanceOf [T0] () : T0

    attributes: final
    definition classes: AnyRef

  5. def $isInstanceOf [T0] () : Boolean

    attributes: final
    definition classes: AnyRef

  6. def == ( arg0 : AnyRef ) : Boolean

    o == arg0 is the same as if (o eq null) arg0 eq null else o.equals(arg0).

    o == arg0 is the same as if (o eq null) arg0 eq null else o.equals(arg0).

    arg0

    the object to compare against this object for equality.

    returns

    true if the receiver object is equivalent to the argument; false otherwise.

    attributes: final
    definition classes: AnyRef

  7. def == ( arg0 : Any ) : Boolean

    o == arg0 is the same as o.equals(arg0).

    o == arg0 is the same as o.equals(arg0).

    arg0

    the object to compare against this object for equality.

    returns

    true if the receiver object is equivalent to the argument; false otherwise.

    attributes: final
    definition classes: Any

  8. def asInstanceOf [T0] : T0

    This method is used to cast the receiver object to be of type T0.

    This method is used to cast the receiver object to be of type T0.

    Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested typed.

    returns

    the receiver object.

    attributes: final
    definition classes: Any

  9. def canEqual ( arg0 : Any ) : Boolean

    definition classes: MatchResult → Equals

  10. def clone () : AnyRef

    This method creates and returns a copy of the receiver object.

    This method creates and returns a copy of the receiver object.

    The default implementation of the clone method is platform dependent.

    returns

    a copy of the receiver object.

    attributes: protected[lang]
    definition classes: AnyRef
    annotations: @throws()

  11. def eq ( arg0 : AnyRef ) : Boolean

    This method is used to test whether the argument (arg0) is a reference to the receiver object (this).

    This method is used to test whether the argument (arg0) is a reference to the receiver object (this).

    The eq method implements an [http://en.wikipedia.org/wiki/Equivalence_relation equivalence relation] on non-null instances of AnyRef: * It is reflexive: for any non-null instance x of type AnyRef, x.eq(x) returns true. * It is symmetric: for any non-null instances x and y of type AnyRef, x.eq(y) returns true if and only if y.eq(x) returns true. * It is transitive: for any non-null instances x, y, and z of type AnyRef if x.eq(y) returns true and y.eq(z) returns true, then x.eq(z) returns true.

    Additionally, the eq method has three other properties. * It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false. * For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false. * null.eq(null) returns true.

    When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).

    arg0

    the object to compare against this object for reference equality.

    returns

    true if the argument is a reference to the receiver object; false otherwise.

    attributes: final
    definition classes: AnyRef

  12. def equals ( arg0 : Any ) : Boolean

    This method is used to compare the receiver object (this) with the argument object (arg0) for equivalence.

    This method is used to compare the receiver object (this) with the argument object (arg0) for equivalence.

    The default implementations of this method is an [http://en.wikipedia.org/wiki/Equivalence_relation equivalence relation]: * It is reflexive: for any instance x of type Any, x.equals(x) should return true. * It is symmetric: for any instances x and y of type Any, x.equals(y) should return true if and only if y.equals(x) returns true. * It is transitive: for any instances x, y, and z of type AnyRef if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.

    If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is often necessary to override hashCode to ensure that objects that are "equal" (o1.equals(o2) returns true) hash to the same scala.Int (o1.hashCode.equals(o2.hashCode)).

    arg0

    the object to compare against this object for equality.

    returns

    true if the receiver object is equivalent to the argument; false otherwise.

    definition classes: MatchResult → Equals → AnyRef → Any

  13. val failureMessage : String

    a failure message to report if a match fails

    a failure message to report if a match fails

  14. def finalize () : Unit

    This method is called by the garbage collector on the receiver object when garbage collection determines that there are no more references to the object.

    This method is called by the garbage collector on the receiver object when garbage collection determines that there are no more references to the object.

    The details of when and if the finalize method are invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.

    attributes: protected[lang]
    definition classes: AnyRef
    annotations: @throws()

  15. def getClass () : java.lang.Class[_]

    Returns a representation that corresponds to the dynamic class of the receiver object.

    Returns a representation that corresponds to the dynamic class of the receiver object.

    The nature of the representation is platform dependent.

    returns

    a representation that corresponds to the dynamic class of the receiver object.

    attributes: final
    definition classes: AnyRef

  16. def hashCode () : Int

    Returns a hash code value for the object.

    Returns a hash code value for the object.

    The default hashing algorithm is platform dependent.

    Note that it is allowed for two objects to have identical hash codes (o1.hashCode.equals(o2.hashCode)) yet not be equal (o1.equals(o2) returns false). A degenerate implementation could always return 0. However, it is required that if two objects are equal (o1.equals(o2) returns true) that they have identical hash codes (o1.hashCode.equals(o2.hashCode)). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the equals method.

    returns

    the hash code value for the object.

    definition classes: MatchResult → AnyRef → Any

  17. def isInstanceOf [T0] : Boolean

    This method is used to test whether the dynamic type of the receiver object is T0.

    This method is used to test whether the dynamic type of the receiver object is T0.

    Note that the test result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested typed.

    returns

    true if the receiver object is an instance of erasure of type T0; false otherwise.

    attributes: final
    definition classes: Any

  18. val matches : Boolean

    indicates whether or not the matcher matched

    indicates whether or not the matcher matched

  19. val midSentenceFailureMessage : String

    a failure message suitable for appearing mid-sentence

    a failure message suitable for appearing mid-sentence

  20. val midSentenceNegatedFailureMessage : String

    a negated failure message suitable for appearing mid-sentence

    a negated failure message suitable for appearing mid-sentence

  21. def ne ( arg0 : AnyRef ) : Boolean

    o.ne(arg0) is the same as !(o.eq(arg0)).

    o.ne(arg0) is the same as !(o.eq(arg0)).

    arg0

    the object to compare against this object for reference dis-equality.

    returns

    false if the argument is not a reference to the receiver object; true otherwise.

    attributes: final
    definition classes: AnyRef

  22. val negatedFailureMessage : String

    a message with a meaning opposite to that of the failure message

    a message with a meaning opposite to that of the failure message

  23. def notify () : Unit

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Wakes up a single thread that is waiting on the receiver object's monitor.

    attributes: final
    definition classes: AnyRef

  24. def notifyAll () : Unit

    Wakes up all threads that are waiting on the receiver object's monitor.

    Wakes up all threads that are waiting on the receiver object's monitor.

    attributes: final
    definition classes: AnyRef

  25. def productArity : Int

    definition classes: MatchResult → Product

  26. def productElement ( arg0 : Int ) : Any

    definition classes: MatchResult → Product

  27. def productElements : Iterator[Any]

    definition classes: Product
    annotations: @deprecated()
      deprecated:

    1. use productIterator instead

  28. def productIterator : Iterator[Any]

    definition classes: Product

  29. def productPrefix : String

    definition classes: MatchResult → Product

  30. def synchronized [T0] ( arg0 : ⇒ T0 ) : T0

    attributes: final
    definition classes: AnyRef

  31. def toString () : String

    Returns a string representation of the object.

    Returns a string representation of the object.

    The default representation is platform dependent.

    returns

    a string representation of the object.

    definition classes: MatchResult → AnyRef → Any

  32. def wait () : Unit

    attributes: final
    definition classes: AnyRef
    annotations: @throws()

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

    attributes: final
    definition classes: AnyRef
    annotations: @throws()

  34. def wait ( arg0 : Long ) : Unit

    attributes: final
    definition classes: AnyRef
    annotations: @throws()