Using Mockito with TestNG

Question

I took a working test written for JUnit using Mockito and tried to adapt it to work with TestNG but oddly using TestNG only one test will work.

I think it is somehow rel

Answer 1

I'm not sure, if this answer fits to the questioners problem, because the mocks are not listed. But I'd like to re-state one comment from andy in the accepted answer, which helped me out on the same problem. Here are some more details and an example:

---

public class B {

private A a;

B (A a) {
    this.a = a
}

// ...

---

import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.Test;


public class MyTest {

    @Mock
    A a;

    @InjectMocks
    B B;

    @BeforeMethod
    public void init() {
        MockitoAnnotations.initMocks(this);
    }

    @Test
    void test1() {
        // ...
        // b.toString();
        // b.getA().toString();
        // a.toString();
    }

    @Test
    void test2() {
        // ...
        // b.toString();
        // b.getA().toString();
        // a.toString();
    }

    @AfterMethod
    public void reset()
    {
        // Solution:
        b = null;
    }
}

---

Mockitos initMocks only re-initializes mocks, as reset only resets mocks. The problem is the class under test, which is annotated with @InjectMocks. This class, here named B is not initialized again. It is initialized for the first test with a mock of A, the mock of A is re-initialized but B still contains the first version of A.

The solution is to reset the class under test manually with b = null at any plausible place (@AfterMethododer before initMocks). Then Mockito also re-inizialized the class under test B.

Answer 2

You can also use MockitoTestNGListener it is similar to JUnit MockitoJUnitRunner or MockitoExtension.

Example of code:

import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.testng.MockitoTestNGListener;
import org.testng.annotations.Listeners;
import org.testng.annotations.Test;

import java.util.Map;

@Listeners(MockitoTestNGListener.class)
public class MyTest {

    @Mock
    Map map;

    @InjectMocks
    SomeType someType;

    @Test
    void test() {
        // ...
    }
}

Answer 3

There is a difference in the behaviour of these frameworks:

• JUnit creates a new instance of class for every of its test methods. This means that the fields are not shared between tests.
• But TestNG creates only one object and thus the state in fields is shared between to @Tests

For Mockito you need to init mocks before every test method so that the state is not shared between two @Tests in TestNG:

@BeforeMethod
public void init() {
    MockitoAnnotations.initMocks(this);
}

For JUnit it works out of box because 2nd @Test has its own fields and its own mocks.