Aaron Aaron - 1 month ago 11
Java Question

How can I mock private static method with PowerMockito?

I'm trying to mock private static method

anotherMethod()
. See code below

public class Util {
public static String method(){
return anotherMethod();
}

private static String anotherMethod() {
throw new RuntimeException(); // logic was replaced with exception.
}
}


Here is me test code

@PrepareForTest(Util.class)
public class UtilTest extends PowerMockTestCase {

@Test
public void should_prevent_invoking_of_private_method_but_return_result_of_it() throws Exception {

PowerMockito.mockStatic(Util.class);
PowerMockito.when(Util.class, "anotherMethod").thenReturn("abc");

String retrieved = Util.method();

assertNotNull(retrieved);
assertEquals(retrieved, "abc");
}
}


But every tile I run it I get this exception

java.lang.AssertionError: expected object to not be null


I suppose that I'm doing something wrong with mocking stuff. Any ideas how can I fix it?

Answer

To to this, you can use PowerMockito.spy(...) and PowerMockito.doReturn(...). Moreover, you have to specify the PowerMock runner at your test class, as follows:

@PrepareForTest(Util.class)
@RunWith(PowerMockRunner.class)
public class UtilTest {

   @Test
   public void testMethod() throws Exception {
      PowerMockito.spy(Util.class);
      PowerMockito.doReturn("abc").when(Util.class, "anotherMethod");

      String retrieved = Util.method();

      Assert.assertNotNull(retrieved);
      Assert.assertEquals(retrieved, "abc");
   }
}

Hope it helps you.

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