Java test

Assignment

Implement very simplified version of Mockito http://site.mockito.org.

What to implement

Methods to implement:

• mock – creates mocked object (proxy)
• when – returns object with one method thenReturn which has to take the same parameter as when method call

Usage

MyClass m = MyMockito.mock(MyClass.class);
MyMockito.when(m.someMethod()).thenReturn(someValue);
m.someMethod(); // returns `someValue`

How to create mock object

Use library CGLib http://mvnrepository.com/artifact/cglib/cglib/3.2.6

Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(classObject); // parameter of mock method
enhancer.setCallback(new MyMockClassCallback());
return (T) enhancer.create(); // T is template arg of mock method

where MyMockClassCallback is a class which looks like this:

private static class MyMockClassCallback implements MethodInterceptor {

    @Override
    public Object intercept(Object o, Method method, Object[] args, MethodProxy methodProxy) { 
        return methodProxy.invokeSuper(o, args); 
    }
}

What to be aware of

It is easy to call different method on o in intercept() which can cause StackOverflowError.

How to run tests

mvn test

or simply run from your IDE :)

Good luck! :)