PowerMock: How to unmock a method?

Question

I have a static method that is mocked using PowerMock to throw an exception. (It deletes files.) Unfortunately, during my @After (after-each-test) method, I need to call this method without the mocks. How can I umock a method?

I don't see an equivalent to Mockito.reset(). [ Ref: mockito : how to unmock a method? ]

Example:

@RunWith(PowerMockRunner.class)
@PrepareForTest(PathUtils.class)  // Important: This class has a static method we want to mock.
public class CleaningServiceImplTest2 extends TestBase {

    public static final File testDirPath = new File(CleaningServiceImplTest2.class.getSimpleName());

    @BeforeClass
    public static void beforeAllTests() throws PathException {
        recursiveDeleteDirectory(testDirPath);
    }

    @AfterClass
    public static void afterAllTests() throws PathException {
        recursiveDeleteDirectory(testDirPath);
    }

    private File randomParentDirPath;
    private CleaningServiceImpl classUnderTest;

    @Before
    public void beforeEachTest() {
        randomParentDirPath = new File(testDirPath, UUID.randomUUID().toString()).getAbsoluteFile();
        classUnderTest = new CleaningServiceImpl(randomParentDirPath);
    }

    @After
    public void afterEachTest() throws PathException {
        recursiveDeleteDirectory(randomParentDirPath);
    }

    public static void recursiveDeleteDirectory(File dirPath) throws PathException {
        // calls PathUtils.removeFile(...)
    }

    @Test
    public void run_FailWhenCannotRemoveFile() throws IOException {
        // We only want to mock one method.  Use spy() and not mockStatic().
        PowerMockito.spy(PathUtils.class);

        // These two statements are tightly bound.
        PowerMockito.doThrow(new PathException(PathException.PathExceptionReason.UNKNOWN, randomParentDirPath, null, "message"))
            .when(PathUtils.class);
        PathUtils.removeFile(Mockito.any(File.class));

        classUnderTest.run();
    }
}

Answer 1

This took me a while to figure out, so I am answering my own question.

AFAIK, you need to "undo" each mock. Mockito.reset() will not work with Class<?> references. At the end of the test method, add:

// Undo the mock above because we need to call PathUtils.removeFile() within @After.
PowerMockito.doCallRealMethod().when(PathUtils.class);
PathUtils.removeFile(Mockito.any(File.class));

Answer 2

The only way you can undo mocking of a static method with PowerMock is when you mock a class at the beginning of a test and then undo the mock at the end of a test. It doesn't matter if you use SPY or a regular mocking.

Tested with:

"org.powermock" % "powermock" % "1.5" % Test,
"org.powermock" % "powermock-api-mockito" % "1.6.1" % Test,

Test class

package mytests;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

import static org.fest.assertions.Assertions.assertThat;


@RunWith(PowerMockRunner.class)
@PrepareForTest({StaticTest.class})
public class TestTest {

    @Before
    public void checkIfOriginalMethodGetsCalled() {

//        PowerMockito.mockStatic(StaticTest.class); if you do this in @Before you are not going to be able to undo it
        assertThat(StaticTest.staticMethod()).isEqualTo("ORIGINAL VALUE");
        assertThat(StaticTest.otherStaticMethod()).isEqualTo("SPY TEST ORIGINAL");
    }

    @Test
    public void test1() {
        assertThat(StaticTest.staticMethod()).isEqualTo("ORIGINAL VALUE");
    }

    @Test
    public void test3_mocking() {
        mock(); // mock or spy static methods in a test, not in @Before 

        Mockito.when(StaticTest.staticMethod()).thenReturn("MOCKED VALUE");
        assertThat(StaticTest.staticMethod()).isEqualTo("MOCKED VALUE");
        assertThat(StaticTest.otherStaticMethod()).isEqualTo("SPY TEST ORIGINAL");

        undoMock(); // undo the mock at the end of each test, not in @After
    }

    private void mock() {
//        PowerMockito.mockStatic(StaticTest.class); both, spy and mockStatic work ok
        PowerMockito.spy(StaticTest.class);
    }

    private void undoMock() {
        PowerMockito.doCallRealMethod().when(StaticTest.class);
        assertThat(StaticTest.staticMethod()).isNull(); // the undo is going to work in the next test, not here yet. 
    }

    @Test
    public void test2() {
        assertThat(StaticTest.staticMethod()).isEqualTo("ORIGINAL VALUE");
    }

    @After
    public void checkIfOriginalMethodGetsCalled_AfterMockUndo() {

        // undoMock(); in @After  doesn't work with static methods
        assertThat(StaticTest.staticMethod()).isEqualTo("ORIGINAL VALUE");
        assertThat(StaticTest.otherStaticMethod()).isEqualTo("SPY TEST ORIGINAL");
    }
}

class StaticTest {
    public static String staticMethod() {
        return "ORIGINAL VALUE";
    }

    public static String otherStaticMethod() {
        return "SPY TEST ORIGINAL";
    }
}