Hi, I wrote a small patch to aid UI developers in testing UiCommon code: http://gerrit.ovirt.org/#/c/31021/ This patch adds a JUnit rule used to set up the necessary UiCommon infrastructure (represented by mock objects) as expected by existing code (hidden expectations represented by static calls). You can also access these (infrastructure) mock objects to stub their behavior, if necessary. Example - UiCommon infrastructure setup per test class: public class MyTest { @ClassRule public static UiCommonSetup setup = new UiCommonSetup(); // This is optional, but often necessary @BeforeClass public static void stubUiCommonInfra() { AsyncDataProvider adp = setup.getMocks().asyncDataProvider(); when(adp.isWindowsOsType(anyInt())).thenReturn(true); } // Actual test code to exercise model instance(s) } Example - UiCommon infrastructure setup per test method: public class MyTest { @Rule public UiCommonSetup setup = new UiCommonSetup(); // This is optional, but often necessary @Before public void stubUiCommonInfra() { AsyncDataProvider adp = setup.getMocks().asyncDataProvider(); when(adp.isWindowsOsType(anyInt())).thenReturn(true); } // Actual test code to exercise model instance(s) } When creating specific model instances (test subjects), stubbing methods to avoid hidden static calls shouldn't be necessary anymore. Regards, Vojtech