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.
Also, if you want to use PrivateMethodTester
to invoke a parameterless private method, you'll need to use
empty parens. Instead of:
targetObject invokePrivate privateParameterlessMethod
You'll need to write:
targetObject invokePrivate privateParameterlessMethod()
- Companion:
- object
Type members
Classlikes
Class whose instances represent an invocation of a private method. Instances of this
class contain the name of the private method (methodName
) and the arguments
to pass to it during the invocation (args
).
The type parameter, T
, is the return type of the private method.
Class whose instances represent an invocation of a private method. Instances of this
class contain the name of the private method (methodName
) and the arguments
to pass to it during the invocation (args
).
The type parameter, T
, is the return type of the private method.
- Value parameters:
- args
zero to many arguments to pass to the private method when invoked
- methodName
a
Symbol
representing the name of the private method to invoke
- Throws:
- NullArgumentException
if
methodName
isnull
Class used via an implicit conversion to enable private methods to be tested.
Class used via an implicit conversion to enable private methods to be tested.
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.
The type parameter, T
, is the return type of the private method.
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.
The type parameter, T
, is the return type of the private method.
- Value parameters:
- methodName
a
Symbol
representing the name of the private method to invoke
- Throws:
- NullArgumentException
if
methodName
isnull
- Companion:
- object
Contains a factory method for instantiating PrivateMethod
objects.
Contains a factory method for instantiating PrivateMethod
objects.
- Companion:
- class
Implicits
Implicits
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.
- Value parameters:
- target
the target object on which to invoke a private method.
- Throws:
- NullArgumentException
if
target
isnull
.