Bug 327765 EPartService will hide a part of another perspective
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
.createApplication();
		MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		MPart saveablePart = BasicFactoryImpl.eINSTANCE.createPart();
		saveablePart.setDirty(beforeDirty);
		saveablePart
				.setContributionURI("platform:/plugin/org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.application.ClientEditor");
		window.getChildren().add(saveablePart);
		initialize(applicationContext, application);
		getEngine().createGui(window);
		ClientEditor editor = (ClientEditor) saveablePart.getObject();
		editor.setThrowException(throwException);
		window.getContext().set(ISaveHandler.class.getName(),
				new ISaveHandler() {
					public Save[] promptToSave(Collection<MPart> saveablePart) {
						return null;
					}
					public Save promptToSave(MPart saveablePart) {
						return returnValue;
					}
				});
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		if (beforeDirty) {
			assertEquals(success, partService.savePart(saveablePart, confirm));
		} else {
			assertTrue(
					"The part is not dirty, the save operation should complete successfully",
					partService.savePart(saveablePart, confirm));
		}