292 bug unexpected vm is created

mvvmfx/src/main/java/de/saxsys/mvvmfx/internal/viewloader/FxmlViewLoader.java

@@ -135,15 +135,27 @@ public <ViewType extends View<? extends ViewModelType>, ViewModelType extends Vi
 				throw new IOException("Could not load the controller for the View " + resource
 						+ " maybe your missed the fx:controller in your fxml?");
 			}
+
+
+			// the actually used ViewModel instance. We need this so we can return it in the ViewTuple
+			ViewModelType actualViewModel;
 
-
-			ViewModelType loadedViewModel = ViewLoaderReflectionUtils.getExistingViewModel(loadedController);
-
-			if (loadedViewModel == null) {
-				loadedViewModel = ViewLoaderReflectionUtils.createViewModel(loadedController);
+			// if no existing viewModel was provided...
+			if(viewModel == null) {
+				// ... we try to find the created ViewModel from the codeBehind.
+				// this is only possible when the codeBehind has a field for the VM and the VM was injected
+				actualViewModel = ViewLoaderReflectionUtils.getExistingViewModel(loadedController);
+
+				// otherwise we create a new ViewModel. This is needed because the ViewTuple has to contain a VM even if the codeBehind doesn't need one
+				if (actualViewModel == null) {
+					actualViewModel = ViewLoaderReflectionUtils.createViewModel(loadedController);
+				}
+			} else {
+				actualViewModel = viewModel;
 			}
 
-			return new ViewTuple<>(loadedController, loadedRoot, loadedViewModel);
+
+			return new ViewTuple<>(loadedController, loadedRoot, actualViewModel);
 
 		} catch (final IOException ex) {
 			throw new RuntimeException(ex);

mvvmfx/src/test/java/de/saxsys/mvvmfx/internal/viewloader/FluentViewLoader_FxmlView_Test.java

@@ -16,13 +16,15 @@
 package de.saxsys.mvvmfx.internal.viewloader;
 
 import de.saxsys.mvvmfx.FluentViewLoader;
+import de.saxsys.mvvmfx.MvvmFX;
 import de.saxsys.mvvmfx.ViewTuple;
 import de.saxsys.mvvmfx.internal.viewloader.example.*;
 import de.saxsys.mvvmfx.testingutils.ExceptionUtils;
 import de.saxsys.mvvmfx.testingutils.jfxrunner.JfxRunner;
 import javafx.fxml.LoadException;
 import javafx.scene.layout.VBox;
 import org.junit.Before;
+import org.junit.Ignore;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -341,4 +343,41 @@ public void testViewModelIsAvailableInViewTupleEvenIfItIsntInjectedInTheView() {
 		assertThat(viewTuple.getViewModel()).isNotNull();
 
 	}
+
+	/**
+	 * This test reproduces the <a href="https://github.com/sialcasa/mvvmFX/issues/292">bug #292</a>
+	 * Given the following conditions:
+	 * 1. The View has no ViewModel field and not injection of the ViewModel.
+	 * 2. While loading an existing ViewModel instance is passed to the {@link FluentViewLoader}
+	 * 
+	 * Under this conditions the ViewLoader was still creating a new ViewModel instance or retrieved an instance
+	 * from DI. This isn't expected because the user has passed an existing ViewModel instance into the ViewLoader.
+	 * 
+	 */
+	@Test
+	public void testExistingViewModelWithoutInjectionInView() {
+		DependencyInjector.getInstance().setCustomInjector(type -> {
+			if(type.equals(TestViewModel.class)) {
+				fail("An instance of TestViewModel was requested!");
+				throw new IllegalStateException("An instance of TestViewModel was requested!");
+			} else {
+				try {
+					return type.newInstance();
+				} catch (InstantiationException | IllegalAccessException e) {
+					throw new RuntimeException(e);
+				}
+			}
+		});
+
+
+		TestViewModel viewModel = new TestViewModel();
+
+		final ViewTuple<TestFxmlViewWithoutViewModelField, TestViewModel> viewTuple = FluentViewLoader
+				.fxmlView(TestFxmlViewWithoutViewModelField.class).viewModel(viewModel).load();
+
+		assertThat(viewTuple.getViewModel()).isEqualTo(viewModel);
+
+		// we need to reset the DI
+		DependencyInjector.getInstance().setCustomInjector(null);
+	}
 }