org.scalatest

# PrivateMethodTester

#### trait PrivateMethodTester extends AnyRef

Trait that facilitates the testing of private methods.

To test a private method, mix in trait `PrivateMethodTester` and create a `PrivateMethod` object, like this:

    val decorateToStringValue = PrivateMethod[String]('decorateToStringValue)

The type parameter on `PrivateMethod`, in this case `String`, is the result type of the private method you wish to invoke. The symbol passed to the `PrivateMethod.apply` factory method, in this case `'decorateToStringValue`, is the name of the private method to invoke. To test the private method, use the `invokePrivate` operator, like this:

    targetObject invokePrivate decorateToStringValue(1)

Here, `targetObject` is a variable or singleton object name referring to the object whose private method you want to test. You pass the arguments to the private method in the parentheses after the `PrivateMethod` object. The result type of an `invokePrivate` operation will be the type parameter of the `PrivateMethod`object, thus you need not cast the result to use it. In other words, after creating a `PrivateMethod` object, the syntax to invoke the private method looks like a regular method invocation, but with the dot (`.`) replaced by `invokePrivate`. The private method is invoked dynamically via reflection, so if you have a typo in the method name symbol, specify the wrong result type, or pass invalid parameters, the `invokePrivate` operation will compile, but throw an exception at runtime.

One limitation to be aware of is that you can't use `PrivateMethodTester` to test a private method declared in a trait, because the class the trait gets mixed into will not declare that private method. Only the class generated to hold method implementations for the trait will have that private method. If you want to test a private method declared in a trait, and that method does not use any state of that trait, you can move the private method to a companion object for the trait and test it using `PrivateMethodTester` that way. If the private trait method you want to test uses the trait's state, your best options are to test it indirectly via a non-private trait method that calls the private method, or make the private method package access and test it directly via regular static method invocations.

go to: companion
known subclasses: PrivateMethodTester

authors:

1. Bill Venners

Inherited

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1. AnyRef
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Visibility

1. Public
2. All

### Type Members

1. #### class Invocation[T] extends AnyRef

   Class whose instances represent an invocation of a private method.

2. #### class Invoker extends AnyRef

   Class used via an implicit conversion to enable private methods to be tested.

3. #### class PrivateMethod[T] extends AnyRef

   Represent a private method, whose apply method returns an `Invocation` object that records the name of the private method to invoke, and any arguments to pass to it when invoked.

### 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. #### object PrivateMethod extends AnyRef

   Contains a factory method for instantiating `PrivateMethod` objects.

9. #### implicit def anyRefToInvoker(target: AnyRef): Invoker

   Implicit conversion from `AnyRef` to `Invoker`, used to enable assertions testing of private methods.

   Implicit conversion from `AnyRef` to `Invoker`, used to enable assertions testing of private methods.

   target

     the target object on which to invoke a private method.

   attributes: implicit

10. #### 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

11. #### 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

12. #### 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

13. #### 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

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
    definition classes: AnyRef

15. #### 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

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: 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. #### 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

19. #### 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

20. #### 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

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

    attributes: final
    definition classes: AnyRef

22. #### 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

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

    attributes: final
    definition classes: AnyRef

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

    attributes: final
    definition classes: AnyRef

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

    attributes: final
    definition classes: AnyRef