passing Parameterized input using Mockitos

Question

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 1

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.

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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 */ } } 

Answer 2

If you are stuck with an older version of mockito where MockitoRule isn't available, the other possibility is to initialize the mocks explicitely with MockitoAnnotations.initMocks:

@RunWith(Parameterized.class) public class YourComponentTest {             @Mock YourDep mockYourDep;      @Parameter     public Parameter parameter;      @Parameters public static Collection<Object[]> data() { /* Return the values */ }      @Before     public void init() {         MockitoAnnotations.initMocks(this);     }      @Test public void test() { /* Use the field value in assertions */ } }