CODEWITHSUNDEEP
javaunit-testingjunitjmockit
KidCrippler
KidCrippler

Reputation: 1723

JMockit expectations API - return input parameters

I know that if I want to mock a method and assign a specific behavior to it based on its input, I can do it with the MockUps API:

public class DuplicationTest {

    static class Duplicator {
        public String duplicate(String str) { return null; }
    }

    @Test
    public void verifySameStringReturnedWithMockupsAPI() throws Exception {
        new MockUp<Duplicator>() {
            @Mock public String duplicate(String str) { return str; }
        };

        Duplicator dup = new Duplicator();
        assertEquals("test", dup.duplicate("test"));
    }
}

This test passes.
However, sometimes I don't have the luxury of working with the MockUps API (e.g. when mocking static classes), therefore I can only use the Expectations API:

@Test
public void verifySameStringReturnedWithExpectationsAPI(@Mocked Duplicator dup) throws Exception {
    new Expectations() {{
        dup.duplicate(anyString); result = anyString;
    }};

    assertEquals("test", dup.duplicate("test"));
}

This obviously fails. The call to dup.duplicate("test") returns an empty String (probably some kind of default). Is there any way around it?

Upvotes: 3

Views: 3163

Answers (2)

KidCrippler
KidCrippler

Reputation: 1723

Inspired by a comment made by Rogério, I managed to solve the issue using a Delegate:

@SuppressWarnings("unused")
@Test
public void verifySameStringReturnedWithExpectationsAPI(@Mocked Duplicator dup) throws Exception {
    new Expectations() {{
        dup.duplicate(anyString);
        result = new Delegate<String>() { String delegate(String str) { return str; }};
    }};

    assertEquals("test", dup.duplicate("test"));
    assertEquals("delegate did it", dup.duplicate("delegate did it"));
}

This is not the most elegant solution and could look a lot better if the Delegate class was a @FunctionalInterface (which I understood would happen in the next major release of JMockit). For now, that seems to be the only way to mock behavior according to the input parameters within the Expectations API.

Upvotes: 4

TheEllis
TheEllis

Reputation: 1736

In your second example, it returns an empty String because you are setting result = anyString. anyString is a jmockit object that is used to match any possible string value. What you want to do instead is set result to the value you actually want to return, in this case result = "test".

Upvotes: 0

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