org.scalatest

# Assertions

#### object Assertions extends Assertions

Companion object that facilitates the importing of `Assertions` members as an alternative to mixing it in. One use case is to import `Assertions` members so you can use them in the Scala interpreter:

    $scala -classpath scalatest.jar
    Welcome to Scala version 2.7.3.final (Java HotSpot(TM) Client VM, Java 1.5.0_16).
    Type in expressions to have them evaluated.
    Type :help for more information.scala> import org.scalatest.Assertions._
    import org.scalatest.Assertions._scala> assert(1 === 2)
    org.scalatest.TestFailedException: 1 did not equal 2
    	at org.scalatest.Assertions$class.assert(Assertions.scala:211)
    	at org.scalatest.Assertions$.assert(Assertions.scala:511)
    	at .<init>(<console>:7)
    	at .<clinit>(<console>)
    	at RequestResult$.<init>(<console>:3)
    	at RequestResult$.<clinit>(<console>)
    	at RequestResult$result(<console>)
    	at sun.reflect.NativeMethodAccessorImpl.invoke...scala> expect(3) { 1 + 3 }
    org.scalatest.TestFailedException: Expected 3, but got 4
    	at org.scalatest.Assertions$class.expect(Assertions.scala:447)
    	at org.scalatest.Assertions$.expect(Assertions.scala:511)
    	at .<init>(<console>:7)
    	at .<clinit>(<console>)
    	at RequestResult$.<init>(<console>:3)
    	at RequestResult$.<clinit>(<console>)
    	at RequestResult$result(<console>)
    	at sun.reflect.NativeMethodAccessorImpl.in...scala> val caught = intercept[StringIndexOutOfBoundsException] { "hi".charAt(-1) }
    caught: StringIndexOutOfBoundsException = java.lang.StringIndexOutOfBoundsException: String index out of range: -1

go to: companion

authors:

1. Bill Venners

Inherited

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1. Assertions
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Visibility

1. Public
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### Type Members

1. #### class Equalizer extends AnyRef

   Class used via an implicit conversion to enable any two objects to be compared with`===` in assertions in tests.

### 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 assert(o: Option[String]): Unit

   Assert that an `Option[String]` is `None`.

   Assert that an `Option[String]` is `None`. If the condition is `None`, this method returns normally. Else, it throws `TestFailedException` with the `String`value of the `Some` included in the `TestFailedException`'s detail message.

   This form of `assert` is usually called in conjunction with an implicit conversion to `Equalizer`, using a `===` comparison, as in:

       assert(a === b)

   For more information on how this mechanism works, see the documentation for`Equalizer`.

   o

     the `Option[String]` to assert

   definition classes: Assertions

10. #### def assert(o: Option[String], clue: Any): Unit

    Assert that an `Option[String]` is `None`.

    Assert that an `Option[String]` is `None`. If the condition is `None`, this method returns normally. Else, it throws `TestFailedException` with the `String`value of the `Some`, as well as the`String` obtained by invoking `toString` on the specified `message`, included in the `TestFailedException`'s detail message.

    This form of `assert` is usually called in conjunction with an implicit conversion to `Equalizer`, using a `===` comparison, as in:

        assert(a === b, "extra info reported if assertion fails")

    For more information on how this mechanism works, see the documentation for`Equalizer`.

    o

      the `Option[String]` to assert

    clue

      An objects whose `toString` method returns a message to include in a failure report.

    definition classes: Assertions

11. #### def assert(condition: Boolean, clue: Any): Unit

    Assert that a boolean condition, described in `String` `message`, is true.

    Assert that a boolean condition, described in `String` `message`, is true. If the condition is `true`, this method returns normally. Else, it throws `TestFailedException` with the`String` obtained by invoking `toString` on the specified `message` as the exception's detail message.

    condition

      the boolean condition to assert

    clue

      An objects whose `toString` method returns a message to include in a failure report.

    definition classes: Assertions

12. #### def assert(condition: Boolean): Unit

    Assert that a boolean condition is true.

    Assert that a boolean condition is true. If the condition is `true`, this method returns normally. Else, it throws `TestFailedException`.

    condition

      the boolean condition to assert

    definition classes: Assertions

13. #### 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
    definition classes: AnyRef

14. #### implicit def convertToEqualizer(left: Any): Equalizer

    Implicit conversion from `Any` to `Equalizer`, used to enable assertions with `===` comparisons.

    Implicit conversion from `Any` to `Equalizer`, used to enable assertions with `===` comparisons.

    For more information on this mechanism, see the documentation for Equalizer.

    Because trait `Suite` mixes in `Assertions`, this implicit conversion will always be available by default in ScalaTest `Suite`s. This is the only implicit conversion that is in scope by default in every ScalaTest `Suite`. Other implicit conversions offered by ScalaTest, such as those that support the matchers DSL or `invokePrivate`, must be explicitly invited into your test code, either by mixing in a trait or importing the members of its companion object. The reason ScalaTest requires you to invite in implicit conversions (with the exception of the implicit conversion for `===` operator) is because if one of ScalaTest's implicit conversions clashes with an implicit conversion used in the code you are trying to test, your program won't compile. Thus there is a chance that if you are ever trying to use a library or test some code that also offers an implicit conversion involving a `===` operator, you could run into the problem of a compiler error due to an ambiguous implicit conversion. If that happens, you can turn off the implicit conversion offered by this `convertToEqualizer` method simply by overriding the method in your`Suite` subclass, but not marking it as implicit:

        // In your Suite subclass
        override def convertToEqualizer(left: Any) = new Equalizer(left)

    left

      the object whose type to convert to `Equalizer`.

    attributes: implicit
    definition classes: Assertions

15. #### 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

16. #### 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: AnyRef → Any

17. #### def expect(expected: Any)(actual: Any): Unit

    Expect that the value passed as `expected` equals the value passed as `actual`.

    Expect that the value passed as `expected` equals the value passed as `actual`. If the `actual` value equals the `expected` value (as determined by `==`), `expect` returns normally. Else, `expect` throws an`TestFailedException` whose detail message includes the expected and actual values.

    expected

      the expected value

    actual

      the actual value, which should equal the passed `expected` value

    definition classes: Assertions

18. #### def expect(expected: Any, clue: Any)(actual: Any): Unit

    Expect that the value passed as `expected` equals the value passed as `actual`.

    Expect that the value passed as `expected` equals the value passed as `actual`. If the `actual` equals the `expected`(as determined by `==`), `expect` returns normally. Else, if `actual` is not equal to `expected`, `expect` throws an`TestFailedException` whose detail message includes the expected and actual values, as well as the `String`obtained by invoking `toString` on the passed `message`.

    expected

      the expected value

    clue

      An object whose `toString` method returns a message to include in a failure report.

    actual

      the actual value, which should equal the passed `expected` value

    definition classes: Assertions

19. #### def fail(cause: Throwable): Nothing

    Throws `TestFailedException`, with the passed`Throwable` cause, to indicate a test failed.

    Throws `TestFailedException`, with the passed`Throwable` cause, to indicate a test failed. The `getMessage` method of the thrown `TestFailedException`will return `cause.toString()`.

    cause

      a `Throwable` that indicates the cause of the failure.

    definition classes: Assertions

20. #### def fail(message: String, cause: Throwable): Nothing

    Throws `TestFailedException`, with the passed`String` `message` as the exception's detail message and `Throwable` cause, to indicate a test failed.

    Throws `TestFailedException`, with the passed`String` `message` as the exception's detail message and `Throwable` cause, to indicate a test failed.

    message

      A message describing the failure.

    cause

      A `Throwable` that indicates the cause of the failure.

    definition classes: Assertions

21. #### def fail(message: String): Nothing

    Throws `TestFailedException`, with the passed`String` `message` as the exception's detail message, to indicate a test failed.

    Throws `TestFailedException`, with the passed`String` `message` as the exception's detail message, to indicate a test failed.

    message

      A message describing the failure.

    definition classes: Assertions

22. #### def fail(): Nothing

    Throws `TestFailedException` to indicate a test failed.

    Throws `TestFailedException` to indicate a test failed.

    definition classes: Assertions

23. #### 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
    definition classes: AnyRef

24. #### def getClass(): java.lang.Class[_ <: java.lang.Object]

    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

25. #### 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: AnyRef → Any

26. #### def intercept[T <: AnyRef](f: ⇒ Any)(implicit manifest: Manifest[T]): T

    Intercept and return an exception that's expected to be thrown by the passed function value.

    Intercept and return an exception that's expected to be thrown by the passed function value. The thrown exception must be an instance of the type specified by the type parameter of this method. This method invokes the passed function. If the function throws an exception that's an instance of the specified type, this method returns that exception. Else, whether the passed function returns normally or completes abruptly with a different exception, this method throws `TestFailedException`.

    Note that the type specified as this method's type parameter may represent any subtype of`AnyRef`, not just `Throwable` or one of its subclasses. In Scala, exceptions can be caught based on traits they implement, so it may at times make sense to specify a trait that the intercepted exception's class must mix in. If a class instance is passed for a type that could not possibly be used to catch an exception (such as `String`, for example), this method will complete abruptly with a `TestFailedException`.

    f

      the function value that should throw the expected exception

    manifest

      an implicit `Manifest` representing the type of the specified type parameter.

    returns

      the intercepted exception, if it is of the expected type

    definition classes: Assertions

27. #### 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

28. #### 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

29. #### 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

30. #### 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

31. #### def synchronized[T0](arg0: T0): T0

    attributes: final
    definition classes: AnyRef

32. #### 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: AnyRef → Any

33. #### def wait(): Unit

    attributes: final
    definition classes: AnyRef

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

    attributes: final
    definition classes: AnyRef

35. #### def wait(arg0: Long): Unit

    attributes: final
    definition classes: AnyRef