如何使用EasyMock测试模拟方法

Question

I try to test a method in my object using easyMock. I do something like this:

MyObject myObject = createMock(MyObject.class);
expect(myObject.someMethod()).andReturn(someReturn);
replay(myObject);
myObject.methodIwantToTest(); // here assertion or sth like this
verify(myObject);

The code like this is throw an exception that methodIwantToTest is not expected. How to test this method?

Answer 1

Mocks are intended to replace a dependency for a class your are testing. That means if you are testing class A, and it calls a method on class B, you mock class B with the expected behavior, so you can test A in isolation.

You are receiving that error because when you mock a class, you are not supposed to use it normally. You are supposed to set up expectations, and then use your mock in concert with another class. You never set up the expectation that methodIwantToTest should be called, so when you called it, there is an error (since it wasn't expected by the framework).

That said, you can create a partial mock. See this documentation and look for "Partial", where you only mock certain methods.

Answer 2

Just as hvgotcodes said, Mocks are objects used to simulate the dependencies of your Class Under Test(CUT) so that your CUT can be tested in isolation from other code.

Though available, it is generally not advisable to use Partial Mocks . The argument placed is that, when the design of your software is good the use of partial mocks is not necessary. However in some scenarios it may be important to use partial mocks. In your case, partial mocking can be done as follows,

@Test
public void testSomething(){
    MyObject myObject = createMockBuilder(MyObject.class)
       .addMockedMethod("someMethod").createMock();
    expect(myObject.someMethod()).andReturn(someReturn);
    replay(myObject);
    myObject.methodIwantToTest();
    verify(myObject);
}