"mvn test" did not execute @Mock annotated method-CodePudding

I have a test class that looks like this:

import org.junit.Before;
import org.junit.Test;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.MockitoAnnotations;

public class SomeTest {
    @Mock
    Object someObj;

    @Before
    public void before() {
        MockitoAnnotations.openMocks(this);
    }

    @Test
    public void testNullPointer() {
        Mockito.when(someObj.toString()).thenReturn("1");
    }
}

When I run mvn clean test under the root directory of this project, it said that the testcase triggeredNullPointerException, stack tree shows that someObj is null.
I was using org.mockito::mockito-core::4.0.0 and junit::junit::4.13.0.
Seems like before() method is not executed. Any ideas why? Tks in advance.

CodePudding user response：

You are missing annotation on your class:

@RunWith(MockitoJUnitRunner.class)
public class SomeServiceTest {
    ...
}

CodePudding user response：

When running this test you'll get this error above the stacktrace:

testNullPointer(org.example.SomeTest)  Time elapsed: 0.368 sec  <<< ERROR!
org.mockito.exceptions.misusing.MissingMethodInvocationException:
when() requires an argument which has to be 'a method call on a mock'.
For example:
    when(mock.getArticles()).thenReturn(articles);

Also, this error might show up because:
1. you stub either of: final/private/equals()/hashCode() methods.
   Those methods *cannot* be stubbed/verified.
   Mocking methods declared on non-public parent classes is not supported.
2. inside when() you don't call method on mock but on some other object.

The interesting part here is the first bullet - you cannot stub the hashCode method. If you replace it by some method that can be stubbed, the test will pass. E.g.:

Mockito.when(someObj.toString()).thenReturn("yay!");