PowerMocking static does not return expected object - mockito

Question

I have a problem mocking Calendar.getInstance(). As you now this method returns a Calendar - the object I am mocking.
Right now my code looks like this:
#RunWith(PowerMockRunner.class)
#PrepareForTest(Calendar.class)
public class SurveillanceDatabaseTest {
#Test
public void testFailingDatabase() throws Exception {
mockStatic(Calendar.class);
Calendar calendar = new GregorianCalendar();
calendar.add(Calendar.HOUR, 1);
when(Calendar.getInstance()).thenReturn(calendar);
final Surveillance surveillance = new Surveillance();
surveillance.checkDatabase();
}
}
Calendar.getInstance() gets called various times in surveillance.checkDatabase() and every time it is a new object and not the expected mock of Calendar.
Can anyone see what I am doing wrong?

Answer 1

It seems that you need to add the target test class in the PrepareForTest tag:
#PrepareForTest({ Calendar.class, Surveillance.class })
#RunWith(PowerMockRunner.class)
#PrepareForTest({ Calendar.class, Surveillance.class })
public class SurveillanceDatabaseTest {
#Test
public void testFailingDatabase() throws Exception {
mockStatic(Calendar.class);
Calendar calendar = new GregorianCalendar();
calendar.add(Calendar.HOUR, 1);
when(Calendar.getInstance()).thenReturn(calendar);
final Surveillance surveillance = new Surveillance();
surveillance.checkDatabase();
}
}
Even Tom Tresansky's example above will need it if we move the Surveillance class to somewhere outside MockCalendarTest class.

Answer 2

I'm not as familiar with the when(object.call()).andReturn(response); but I'm assuming it works the same way as expect.(object.call()).andReturn(response);. If that is the case, then it looks like all you are missing a replay of the class PowerMock.replay(Calendar.class) and you are trying to do a full static mock instead of a partial static mock. This should resolve your issue.
#RunWith(PowerMockRunner.class)
#PrepareForTest(Calendar.class)
public class SurveillanceDatabaseTest {
#Test
public void testFailingDatabase() throws Exception {
Calendar calendar = new GregorianCalendar();
calendar.add(Calendar.HOUR, 1);
PowerMock.mockStaticPartial(Calendar.class, "getInstance"); //Mock Static Partial
expect(Calendar.getInstance()).andReturn(calendar);
PowerMock.replay(Calendar.class); // note the replay of the Class!
final Surveillance surveillance = new Surveillance();
surveillance.checkDatabase();
//Whatever tests you need to do here
}
}

Answer 3

It seems like you're doing everything right. For instance, this test below passes, proving that the Calendar returned by Calendar#getInstance() is in fact the one you set up with the static mocking.
import static org.junit.Assert.*;
import static org.powermock.api.mockito.PowerMockito.*;
import java.util.Calendar;
import java.util.GregorianCalendar;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
#RunWith(PowerMockRunner.class)
#PrepareForTest(Calendar.class)
public class MockCalendarTest {
#Test
public void testFailingDatabase() {
mockStatic(Calendar.class);
final Calendar testCalendar = new GregorianCalendar();
testCalendar.add(Calendar.HOUR, 1);
when(Calendar.getInstance()).thenReturn(testCalendar);
final Surveillance surveillance = new Surveillance();
final Calendar resultCalendar = surveillance.checkDatabase();
assertTrue(testCalendar == resultCalendar);
}
public static class Surveillance {
public Calendar checkDatabase() {
return Calendar.getInstance();
}
}
}
Perhaps post the relevant parts of the Surveillance class so we can see how it's trying to get a new Calendar and assess why it's failing.