Getting ready

When you take a look at Mockito's TestNG subproject on the Mockito GitHub repository, you will find that there are three classes in the org.mockito.testng package, as follows:

Unfortunately, until this project eventually gets released, you have to just copy and paste those classes to your codebase.

How to do it...

To integrate TestNG and Mockito, perform the following steps:

Now let's take a look at this snippet that, using TestNG, checks whether the mean tax factor value has been calculated properly (remember that I'm using the BDDMockito.given(...) and AssertJ's BDDAssertions.then(...) static methods—refer to Chapter 7, Verifying Behavior with Object Matchers, on how to work with Hamcrest assertThat(...) method):

@Listeners(MockitoTestNGListener.class)
public class MeanTaxFactorCalculatorTestNgTest {

    static final double TAX_FACTOR = 10;

    @Mock TaxService taxService;

    @InjectMocks MeanTaxFactorCalculator systemUnderTest;

    @Test
    public void should_calculate_mean_tax_factor() {
        // given
        given(taxService.getCurrentTaxFactorFor(any(Person.class))).willReturn(TAX_FACTOR);

        // when
        double meanTaxFactor = systemUnderTest.calculateMeanTaxFactorFor(new Person());

        // then
        then(meanTaxFactor).isEqualTo(TAX_FACTOR);
    }

}

How it works...

TestNG allows you to register custom listeners (your listener class has to implement the IInvokedMethodListener interface). Once you do this, the logic inside the implemented methods will be executed before and after every configuration, and test methods get called. Mockito provides you with a listener whose responsibilities are as follows:

See also