CODEWITHSUNDEEP
javaunit-testingcompiler-errorseasymock
Bjarke Freund-Hansen
Bjarke Freund-Hansen

Reputation: 30128

Compile error while using EasyMock.expect() in very simple example?

I am trying a very simple example using EasyMock, however I simply cannot make it build. I have the following test case:

@Test
public void testSomething()
{
    SomeInterface mock = EasyMock.createMock(SomeInterface.class);
    SomeBase expected = new DerivesFromSomeBase();

    EasyMock.expect(mock.send(expected));
}

However I get the following error in the EasyMock.expect(... line:

The method expect(T) in the type EasyMock is not applicable for the arguments (void)

Can somebody point me in the correct direction? I am completely lost.

Upvotes: 8

Views: 16193

Answers (4)

Jasper
Jasper

Reputation: 2176

If you want to test void methods, call the method you want to test on your mock. Then call the expectLastCall() method.

Here's an example:

@Test
public void testSomething()
{
    SomeInterface mock = EasyMock.createMock(SomeInterface.class);
    SomeBase expected = new DerivesFromSomeBase();

    mock.send(expected);

    EasyMock.expectLastCall().andAnswer(new IAnswer<Object>() {
        public Object answer() {
            // do additional assertions here
            SomeBase arg1 = (SomeBase) EasyMock.getCurrentArguments()[0];

            // return null because of void
            return null;
        }
    });
}

Upvotes: 10

Mike Partridge
Mike Partridge

Reputation: 5281

You can't script methods with a void return in that way; check out this question for a good answer on how you can mock the behavior of your send method on your expected object.

Upvotes: 0

Joshua Marble
Joshua Marble

Reputation: 560

Since you are mocking an interface, the only purpose in mocking a method would be to return a result from that method. In this case, it appears your 'send' method's return type is void. The 'EasyMock.expect' method is generic and expects a return type, which is causing the compiler to tell you that you can't use a void method because it doesn't have a return type.

For more information, see the EasyMock API documentation at http://easymock.org/api/easymock/3.0/index.html.

Upvotes: 0

Biju Kunjummen
Biju Kunjummen

Reputation: 49915

Since your send() method returns void, just call the mock method with expected values and replay:

SomeInterface mock = EasyMock.createMock(SomeInterface.class);
SomeBase expected = new DerivesFromSomeBase(); 
mock.send(expected);
replay(mock);

Upvotes: 9

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