Java – Is it possible to create a mock object that implements multiple interfaces with EasyMock

easymockjavamockingrhino-mocksunit-testing

Is it possible to create a mock object that implements several interfaces with EasyMock?

For example, interface Foo and interface Closeable?

In Rhino Mocks you can provide multiple interfaces when creating a mock object, but EasyMock's createMock() method only takes one type.

Is it possbile to achieve this with EasyMock, without resorting to the fallback of creating a temporary interface that extends both Foo and Closeable, and then mocking that?

Best Solution

Although I fundamentally agree with Nick Holt's answer, I thought I should point out that mockito allows to do what you ask with the following call :

Foo mock = Mockito.mock(Foo.class, withSettings().extraInterfaces(Bar.class));

Obviously you'll have to use the cast: (Bar)mock when you need to use the mock as a Bar but that cast will not throw ClassCastException

Here is an example that is a bit more complete, albeit totally absurd:

import static org.junit.Assert.fail;
import org.junit.Test;
import static org.mockito.Mockito.*;
import org.mockito.Mockito;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.*;
import org.hamcrest.Matchers;

import java.util.Iterator;


public class NonsensicalTest {


    @Test
    public void testRunnableIterator() {
        // This test passes.

        final Runnable runnable = 
                    mock(Runnable.class, withSettings().extraInterfaces(Iterator.class));
        final Iterator iterator = (Iterator) runnable;
        when(iterator.next()).thenReturn("a", 2);
        doThrow(new IllegalStateException()).when(runnable).run();

        assertThat(iterator.next(), is(Matchers.<Object>equalTo("a")));

        try {
            runnable.run();
            fail();
        }
        catch (IllegalStateException e) {
        }
    }