FragmentController { public void clearBackStack() { this.assertNotDestroyed("CLEAR BACK STACK"); final int n = manager.getBackStackEntryCount(); for (int i = 0; i < n; i++) { manager.popBackStack(); } } FragmentController(@NonNull final FragmentActivity parentActivity);  FragmentController(@NonNull final Fragment parentFragment);  FragmentController(@NonNull final FragmentManager fragmentManager);  FragmentController(@Nullable final Context context, @NonNull final FragmentManager fragmentManager); @NonNull FragmentManager getFragmentManager(); void setViewContainerId(@IdRes final int containerId); @IdRes int getViewContainerId(); void setFactory(@Nullable final FragmentFactory factory); boolean hasFactory(); @Nullable FragmentFactory getFactory(); void setRequestInterceptor(@Nullable final FragmentRequestInterceptor interceptor); void registerOnRequestListener(@NonNull final OnRequestListener listener); void unregisterOnRequestListener(@NonNull final OnRequestListener listener); void registerOnBackStackChangeListener(@NonNull final OnBackStackChangeListener listener); void unregisterOnBackStackChangeListener(@NonNull final OnBackStackChangeListener listener); @NonNull final FragmentRequest newRequest(); @NonNull final FragmentRequest newRequest(@NonNull final Fragment fragment); @NonNull final FragmentRequest newRequest(final int fragmentId); @SuppressWarnings("NewApi") @NonNull FragmentTransaction createTransaction(@NonNull final FragmentRequest request); @Nullable Fragment findCurrentFragment(); @Nullable Fragment findFragmentByFactoryId(final int factoryFragmentId); boolean hasBackStackEntries(); @Nullable FragmentManager.BackStackEntry getTopBackStackEntry(); void clearBackStack(); boolean clearBackStackImmediate(); final void destroy(); static final String FRAGMENT_TAG; static final int NO_CONTAINER_ID; }
@Test public void testClearBackStack() { final FragmentManager mockManager = mock(FragmentManager.class); final FragmentController controller = new FragmentController(mockManager); when(mockManager.getBackStackEntryCount()).thenReturn(5); controller.clearBackStack(); verify(mockManager, times(2)).getBackStackEntryCount(); verify(mockManager, times(5)).popBackStack(); }
@Test public void testClearBackStackOnEmptyBackStack() { final FragmentManager mockManager = mock(FragmentManager.class); final FragmentController controller = new FragmentController(mockManager); when(mockManager.getBackStackEntryCount()).thenReturn(0); controller.clearBackStack(); verify(mockManager, times(2)).getBackStackEntryCount(); }
@Test(expected = IllegalStateException.class) public void testClearBackStackWhenDestroyed() { createDestroyedController().clearBackStack(); }