spal spal - 15 days ago 10
Java Question

passing Parameterized input using Mockitos

I am using Mockito for unit testing. I am wondering if its possible to send Parametrized input parameters with as in Junit testing

e.g

@InjectMocks
MockClass mockClass = new MockClass();

@Test
public void mockTestMethod()
{
mockClass.testMethod(stringInput);
// here I want to pass a list of String inputs
// this is possible in Junit through Parameterized.class..
// wondering if its can be done in Mockito
}

Answer

In JUnit, Parameterized tests use a special runner that ensure that the test is instantiated multiple times, so each test method is called multiple times. Mockito is a tool for writing specific unit tests, so there is no built-in ability to run the same test multiple times with different Mockito expectations.

If you want your test conditions to change, your best bet is to do one of the following:

  • Parameterize your test using JUnit, with a parameter for the mock inputs you want;
  • Run a loop of different parameters in your test, which unfortunately avoids the "test one thing per method" philosophy
  • Extract a method that actually performs the test, and create a new @Test method for each mock you want.

Note that there's no prohibition on using mock objects as @Parameterized test parameters. If you're looking to parameterize based on mocks, you can do that, possibly creating the mock and setting the expectations in a static method on the test.


Note about runners: This Parameterized test runner conflicts with Mockito's MockitoJUnitRunner: Each test class can only have one runner. You'll want to switch to @Before and @After methods or a Mockito JUnit4 rule for your setup, if you use them both.

As an example, compressed from a different answer that explains more about Parameterized runners versus JUnit rules and lifting from the JUnit4 Parameterized Test doc page and MockitoRule doc page:

@RunWith(Parameterized.class)
public class YourComponentTest {
    @Rule public MockitoRule rule = MockitoJUnit.rule();
    @Mock YourDep mockYourDep;

    @Parameters public static Collection<Object[]> data() { /* Return the values */ }

    public YourComponentTest(Parameter parameter) { /* Save the parameter to a field */ }

    @Test public void test() { /* Use the field value in assertions */ }
}