PowerMock: mocking of static methods (+ return original values in some particular methods)

Question

I use PowerMock 1.4.7 and JUnit 4.8.2

I need to mock only some static methods and I want others (from the same class) just to return original value. When I mock with mockStatic and don't call when().doReturn() all static methods return their defaults - like null when returning Object or false when returning boolean...etc. So I try to use thenCallRealMethod explicitly on each static method to return default implementation (means no mocking/ no fakes) but I don't know how to call it on every possible arguments variations (= I want for every possible input call original method). I only know how to mock concrete argument variation.

Answer 1

You can use a spy on your static class and mock only specific methods:

@RunWith(PowerMockRunner.class)
@PrepareForTest(MyStaticTest.MyStaticClass.class)
public class MyStaticTest {

public static class MyStaticClass {
    public static String getA(String a) {
        return a;
    }
    public static String getB(String b) {
        return b;
    }
}

@Test
public void should_partial_mock_static_class() throws Exception {
    //given
    PowerMockito.spy(MyStaticClass.class);
    given(MyStaticClass.getB(Mockito.anyString())).willReturn("B");
    //then
    assertEquals("A", MyStaticClass.getA("A"));
    assertEquals("B", MyStaticClass.getA("B"));
    assertEquals("C", MyStaticClass.getA("C"));
    assertEquals("B", MyStaticClass.getB("A"));
    assertEquals("B", MyStaticClass.getB("B"));
    assertEquals("B", MyStaticClass.getB("C"));
}

}

Answer 2

You can also use the stubbing API:

stub(method(MyStaticClass.class, "getB")).toReturn("B");

Edit:

To use stub and method statically import methods from these packages:

1. org.powermock.api.support.membermodification.MemberModifier
2. org.powermock.api.support.membermodification.MemberMatcher

For more info refer to the documentation