CODEWITHSUNDEEP
javajakarta-eejunitmockito
MauriceNino
MauriceNino

Reputation: 6747

Testing void methods that do not change anything in Test scenario

I know that every method that doesn't do anything shouldn't be tested (or not even exist). The thing is, that my method does something normally, but for the test-scenario I have to mock that thing that it does. But I would still like to assert the parameters that it would send to the external thing.

Sounds more complicated than it is - Check my snippet for better understanding:

class A {
    @Inject
    private Mailer mailer; // Custom mailer class

    public void doSomething() {
        Date date = new Date(); // dynamic parameter I do not care about in the test
        String parameter = "test"; // The parameter I want to test later

        mailer.sendMail(parameter, date);
    }
}

class ATest {
    @Mock
    @Produces
    private Mailer mailer;

    @Inject
    private A classToTest;

    @Test
    public void testDoSomething() throws Exception {

        classToTest.doSomething();

        assertThat(??).isEqualTo("test"); //How can I get the value of parameter?
    }
}

As you can see I need to mock my emailer, so that I dont send a email everytime a test runs.

It would make no sense to promote parameter to a global variable.

Is there any way to test the value of parameter without changing the code of A? And if not what would be the best solution without messing up my class just for testing?

Upvotes: 1

Views: 271

Answers (2)

David Lavender
David Lavender

Reputation: 8311

You need to use Mockito.verify:

verify(mailer, times(1)).sendMail("test");

Verify checks what happened with your mocks: how many times a method was called, and what arguments were given to that method.

Update: If you want to exclude certain parameters, you can use org.mockito.Matchers.any - easier to have it as a static import. (NB: if you do ignore some parameters, then the ones you want to INCLUDE now have to be wrapped in org.mockito.Matchers.eq).

verify(mailer, times(1)).sendMail(eq("test"), any(Date.class));

Upvotes: 2

GirishB
GirishB

Reputation: 144

One way is to parameterize the method doSomething with a mutable object, that you can set upon method execution and assert in the test method. Otherwise, you may also check for exception thrown for any negative scenario, something like

@Test(expected = EmailSendException.class)
public void testDoSomething(){
    ....
}

Upvotes: 0

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