Question

I use powermock to mock Logger.getInstance() method. This causes a problem as junit seems not to reload classes and after the first test test class has wrong logger instance.

public class LoggedClass {
    public static Logger log = Logger.getInstance();
    ....
}

@RunWith(PowerMockRunner.class)
@PrepareForTest({ LoggedClass.class, Logger.class })
public class SomeTests {
    private Logger log;
    @Before
    public void setUp() {
         PowerMockito.mockStatic(Logger.class);
         log = PowerMockito.mock(Logger.class);
         PowerMockito.when(Logger.getInstance()).thenReturn(log);

         PowerMockito.mockStatic(LoggedClass.class);
    }

    @Test
    public void firstTest() {
         assertTrue(LoggedClass.log == log);
    }

    @Test
    public void secondTest() { // fails
         assertTrue(LoggedClass.log == log);
    }
}

Test fails as LoggedClass has outdated log instance. I could inject explicitly new logger instance, but that is cumbersome when there are lots of static variables that needs to be mocked.

How can I set junit to reload classes every time it runs new test?

Answer 1

The reason the second test fails is that you are creating a new instance of log in your @Before method for each test but since the call to Logger.getInstance() is static it is only happening once. Consider doing what you have in @Before in a @BeforeClass.

There does not seem to be a reason to create a new instance of log for each test. It is a mock and can therefore just be reset.