How to mock static method in overlay type like JsDate.Create()?

[AlexLuya]

I have a class like this:

public class JsDateFake
{
public double getTime()
{
return JsDate.create().getTime();
}
}

Is it possible to mock this static method create() in gwtmockito?

[ekuefler]

Yeah, mocking static methods (especially native ones) is always going to be difficult. I don't think this is something that can be done directly by Mockito or GwtMockito - if you want to make such code testable, you'll probably have to restructure your class slightly to take advantage of dependency injection, either manually or through Gin. For example, you could define a class like this:

class MyClass {
  private final Provider<JsDate> dateProvider;
  @UiField Label time;

  @Inject
  MyClass(Provider<JsDate> dateProvider) {
    this.dateProvider = dateProvider;
  }

  void updateTime() {
    time.setText("The time is " + dateProvider.get().getTime());
  }

With a provider method in a Gin module defined like this:

@Provide
JsDate provideJsDate() {
  return JsDate.create();
}

Then you could test your class like this:

@RunWith(GwtMockitoTestRunner.class)
public class MyClassTest {

  @Mock JsDate date;

  @Test
  public void testUpdateTime() {
    MyClass myClass = new MyClass(Providers.of(date));
    when(date.getTime()).thenReturn(1, 2);

    myClass.updateTime();
    myClass.updateTime();

    verify(myClass.time.setText("The time is 1"));
    verify(myClass.time.setText("The time is 2"));
  }
}

Would that work for you?

[schnatterer]

I experienced a similar issue with static methods in a smart GWT client, where I just couldn't see how to wrap the static method. So I build an (ugly?) extension for StubGenerator that helped me work around the issue.

Do you see an alternative to this approach, or would you extend GwtMockito with this functionality?

The problem is as follows

• In Smart GWT, each component is assigned an ID via SC.generateID()
• GwtMockito's StubGenerator.invoke() will make this method return an empty string.
• This causes an exception in smart GWT's IDManager.validateID(), because empty String does not match the RegEx.

My workaround looks like this

public class StubGenerator {

    // ...

    /**
     * Allows to stub methods, even static ones. Use only if really necessary!
     * Try to use {@link Mockito#mock(Class)} instead!
     *
     * @param clazz the class to stub
     * @param method the method of <code>clazz</code> to stub
     * @param returnValue the value to be returned by <code>clazz.method</code>
     */
    public static void addStubbedMethod(Class<?> clazz, String method, final Object returnValue) {
        STUB_METHODS.put(new ClassAndMethod(clazz, method), new StubMethod() {
            @Override public Object invoke() {
                return returnValue;
            }
        });
    }

    // ...
}

In the test method calling

StubGenerator.addStubbedMethod(SC.class, "generateID", "a" + String.valueOf(System.currentTimeMillis()));

avoids the exception mentioned above.