[FIXED] Do Mock objects get reset for each test?

Issue

I'm using the Mockito framework to create Mock objects in my JUnit tests. Each mock knows what methods have been called on it, so during my tests I can write

verify(myMock, atLeastOnce()).myMethod();

I am wondering if this internal mock knowledge of what it has called will persist across my tests? If it does persist, then I could be getting false positives when using the same verify method in two tests.

A code example

@RunWith(MockitoJUnitRunner.class)
public class EmrActivitiesImplTest {
    
    @Mock private MyClass myMock;
    
    @Before
    public void setup() {
        when(myMock.myMethod()).thenReturn("hello");
    }
    
    @Test
    public void test1() {
        // ..some logic
        verify(myMock, atLeastOnce()).myMethod();
    }
    
    @Test
    public void test2() {
        // ..some other logic
        verify(myMock, atLeastOnce()).myMethod();
    }  
}

Mock state is persisted - test2 will pass regardless, since test1's verify method passed

Mock state is reset - test2 will fail if myMock.myMethod() isn't called

Solution

JUnit creates a new instance of test class each time it runs a new test method and runs @Before method each time it creates a new test class. You can easily test it:

@Before
public void setup() {
    System.out.println("setup");
    when(myMock.myMethod()).thenReturn("hello");
}

And MockitoJUnitRunner will create a new MyMock mock instance for every test method.

Answered By - Evgeniy Dorofeev
Answer Checked By - Candace Johnson (JavaFixing Volunteer)