Mocking an abstract class with a mocked constructor argument?
java, mocking, mockito, spring, unit-testing
Solution
I ended up just using reflection to set a private field in my base class, like so:
// mock the strategy dependency
Strategy strategyMock = mock( Strategy.class);
when(....).thenReturn(...);
// mock the abstract base class
BaseClass baseMock = mock(BaseClass.class, CALLS_REAL_METHODS);
// get the private streategy field
Field strategyField = baseMock.getClass().getSuperclass().getDeclaredField("_privateStrategy");
// make remove final modifier and make field accessible
Field modifiersField = Field.class.getDeclaredField("modifiers");
modifiersField.setAccessible(true);
modifiersField.setInt(strategyField, strategyField.getModifiers() & ~Modifier.FINAL);
strategyField.setAccessible(true);
// set the strategy
strategyField.set(baseMock, strategyMock);
// do unit tests with baseMock
...
It would break if the name of the private field ever changed, but its commented and I can live with that. It's simple, it;s one line of code and I find this preferable to exposing any setters or having to explicitly subclass in my tests.
Edit: So it's not one line of code anymore since my private field needed to be 'final', requiring a some extra reflection code to get around.
Problem
I'd like to use Mockito to unit test an abstract class as detailed in this great answer. The trick is, the abstract class has a dependency on a strategy that gets injected in its constructor. I've created a mock of the strategy and I'd like for my mocked instance of BaseClass to use the mocked strategy for my unit test. Any suggestion as to how I can wire this up? I'm not currently using any IoC framework, but am considering Spring. Perhaps it would do the trick? ``` // abstract class to be tested w/ mock instance abstract BaseClass { // Strategy gets mocked too protected BaseClass( Strategy strategy) { ... } } ``` Update: According to the Mockito mailing list, there currently isn't a way to pass arguments to the constructor of a mock.