Trait extended by matcher objects, which may appear after the word have, that can match against a
property of the type specified by the HavePropertyMatcher's second type parameter P.
HavePropertyMatcher's first type parameter, T, specifies the type that declares the property. The match will succeed if and
only if the value of the property equals the specified value.
The object containing the property
is passed to the HavePropertyMatcher's
apply method. The result is a HavePropertyMatchResult[P].
A HavePropertyMatcher is, therefore, a function from the specified type, T, to
a HavePropertyMatchResult[P].
Although HavePropertyMatcher
and Matcher represent similar concepts, they have no inheritance relationship
because Matcher is intended for use right after should or must
whereas HavePropertyMatcher is intended for use right after have.
A HavePropertyMatcher essentially allows you to write statically typed
property assertions similar to the dynamic ones that use symbols:
book should have ('title ("Moby Dick")) // dynamic: uses reflection
book should have (title ("Moby Dick")) // type safe: only works on Books; no reflection used
One good way to organize custom matchers is to place them inside one or more traits that
you can then mix into the suites or specs that need them. Here's an example that
includes two methods that produce HavePropertyMatchers:
case class Book(val title: String, val author: String)trait CustomMatchers {
def title(expectedValue: String) = new HavePropertyMatcher[Book, String] { def apply(book: Book) = HavePropertyMatchResult( book.title == expectedValue, "title", expectedValue, book.title ) }
def author(expectedValue: String) = new HavePropertyMatcher[Book, String] { def apply(book: Book) = HavePropertyMatchResult( book.author == expectedValue, "author", expectedValue, book.author ) } }
Each time the title method is called, it returns a new HavePropertyMatcher[Book, String] that
can be used to match against the title property of the Book passed to its apply
method. Because the type parameter of these two HavePropertyMatchers is Book, they
can only be used with instances of that type. (The compiler will enforce this.) The match will succeed if the
title property equals the value passed as expectedValue.
If the match succeeds, the matches field of the returned HavePropertyMatchResult will be true.
The second field, propertyName, is simply the string name of the property.
The third and fourth fields, expectedValue and actualValue indicate the expected and actual
values, respectively, for the property.
Here's an example that uses these HavePropertyMatchers:
class ExampleSpec extends Spec with ShouldMatchers with CustomMatchers { describe("A book") {
it("should have the correct title and author") {
val book = Book("Moby Dick", "Melville")
book should have (
title ("Moby Dick"),
author ("Melville")
)
}
}
}
These matches should succeed, but if for example the first property, title ("Moby Dick"), were to fail, you would get an error message like:
The title property had value "A Tale of Two Cities", instead of its expected value "Moby Dick", on object Book(A Tale of Two Cities,Dickens)
For more information on HavePropertyMatchResult and the meaning of its fields, please
see the documentation for HavePropertyMatchResult. To understand why HavePropertyMatcher
is contravariant in its type parameter, see the section entitled "Matcher's variance" in the
documentation for Matcher.
o != arg0 is the same as !(o == (arg0)).
o != arg0 is the same as !(o == (arg0)).
the object to compare against this object for dis-equality.
false if the receiver object is equivalent to the argument; true otherwise.
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).
the object to compare against this object for equality.
true if the receiver object is equivalent to the argument; false otherwise.
o == arg0 is the same as o.equals(arg0).
o == arg0 is the same as o.equals(arg0).
the object to compare against this object for equality.
true if the receiver object is equivalent to the argument; false otherwise.
Check to see if a property on the specified object, objectWithProperty, matches its
expected value, and report the result in
the returned HavePropertyMatchResult. The objectWithProperty is
usually the value to the left of a should or must invocation. For example, book
would be passed as the objectWithProperty in:
Check to see if a property on the specified object, objectWithProperty, matches its
expected value, and report the result in
the returned HavePropertyMatchResult. The objectWithProperty is
usually the value to the left of a should or must invocation. For example, book
would be passed as the objectWithProperty in:
book should have (title ("Moby Dick"))
the object with the property against which to match
the HavePropertyMatchResult that represents the result of the match
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.
the receiver object.
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.
a copy of the receiver object.
Compose this HavePropertyMatcher with the passed function, returning a new HavePropertyMatcher.
Compose this HavePropertyMatcher with the passed function, returning a new HavePropertyMatcher.
This method overrides compose on Function1 to
return a more specific function type of HavePropertyMatcher.
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).
the object to compare against this object for reference equality.
true if the argument is a reference to the receiver object; false otherwise.
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)).
the object to compare against this object for equality.
true if the receiver object is equivalent to the argument; false otherwise.
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.
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.
a representation that corresponds to the dynamic class of the receiver object.
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.
the hash code value for the object.
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.
true if the receiver object is an instance of erasure of type T0; false otherwise.
o.ne(arg0) is the same as !(o.eq(arg0)).
o.ne(arg0) is the same as !(o.eq(arg0)).
the object to compare against this object for reference dis-equality.
false if the argument is not a reference to the receiver object; true otherwise.
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.
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.
Returns a string representation of the object.
Returns a string representation of the object.
The default representation is platform dependent.
a string representation of the object.
Trait extended by matcher objects, which may appear after the word
have, that can match against a property of the type specified by theHavePropertyMatcher's second type parameterP.HavePropertyMatcher's first type parameter,T, specifies the type that declares the property. The match will succeed if and only if the value of the property equals the specified value. The object containing the property is passed to theHavePropertyMatcher'sapplymethod. The result is aHavePropertyMatchResult[P]. AHavePropertyMatcheris, therefore, a function from the specified type,T, to aHavePropertyMatchResult[P].Although
HavePropertyMatcherandMatcherrepresent similar concepts, they have no inheritance relationship becauseMatcheris intended for use right aftershouldormustwhereasHavePropertyMatcheris intended for use right afterhave.A
HavePropertyMatcheressentially allows you to write statically typed property assertions similar to the dynamic ones that use symbols:book should have ('title ("Moby Dick")) // dynamic: uses reflection book should have (title ("Moby Dick")) // type safe: only works on Books; no reflection usedOne good way to organize custom matchers is to place them inside one or more traits that you can then mix into the suites or specs that need them. Here's an example that includes two methods that produce
HavePropertyMatchers:Each time the
titlemethod is called, it returns a newHavePropertyMatcher[Book, String]that can be used to match against thetitleproperty of theBookpassed to itsapplymethod. Because the type parameter of these twoHavePropertyMatchers isBook, they can only be used with instances of that type. (The compiler will enforce this.) The match will succeed if thetitleproperty equals the value passed asexpectedValue. If the match succeeds, thematchesfield of the returnedHavePropertyMatchResultwill betrue. The second field,propertyName, is simply the string name of the property. The third and fourth fields,expectedValueandactualValueindicate the expected and actual values, respectively, for the property. Here's an example that uses theseHavePropertyMatchers:class ExampleSpec extends Spec with ShouldMatchers with CustomMatchers {describe("A book") {
it("should have the correct title and author") {
val book = Book("Moby Dick", "Melville")
book should have ( title ("Moby Dick"), author ("Melville") ) } } }
These matches should succeed, but if for example the first property,
title ("Moby Dick"), were to fail, you would get an error message like:For more information on
HavePropertyMatchResultand the meaning of its fields, please see the documentation forHavePropertyMatchResult. To understand whyHavePropertyMatcheris contravariant in its type parameter, see the section entitled "Matcher's variance" in the documentation forMatcher.