@Before public void setUp() { PowerMockito.mockStatic(Arguments.class); PowerMockito.when(Arguments.createArray()) .thenAnswer( new Answer<Object>() { @Override public Object answer(InvocationOnMock invocation) throws Throwable { return new SimpleArray(); } }); PowerMockito.when(Arguments.createMap()) .thenAnswer( new Answer<Object>() { @Override public Object answer(InvocationOnMock invocation) throws Throwable { return new SimpleMap(); } }); mCatalystInstanceMock = ReactTestHelper.createMockCatalystInstance(); mReactContext = new ReactApplicationContext(RuntimeEnvironment.application); mReactContext.initializeWithInstance(mCatalystInstanceMock); DisplayMetrics displayMetrics = mReactContext.getResources().getDisplayMetrics(); DisplayMetricsHolder.setWindowDisplayMetrics(displayMetrics); UIManagerModule uiManagerModuleMock = mock(UIManagerModule.class); when(mCatalystInstanceMock.getNativeModule(UIManagerModule.class)) .thenReturn(uiManagerModuleMock); }