Lower requirements of pde.junit.runtime and simplify/clean-up its code

ui/org.eclipse.pde.junit.runtime/.classpath

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <classpath>
-	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-17"/>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.8"/>
 	<classpathentry kind="con" path="org.eclipse.pde.core.requiredPlugins"/>
 	<classpathentry kind="src" path="src"/>
 	<classpathentry kind="output" path="bin"/>

ui/org.eclipse.pde.junit.runtime/.settings/org.eclipse.jdt.core.prefs

@@ -8,9 +8,9 @@ org.eclipse.jdt.core.circularClasspath=error
 org.eclipse.jdt.core.classpath.exclusionPatterns=enabled
 org.eclipse.jdt.core.classpath.multipleOutputLocations=enabled
 org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
-org.eclipse.jdt.core.compiler.codegen.targetPlatform=17
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.8
 org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
-org.eclipse.jdt.core.compiler.compliance=17
+org.eclipse.jdt.core.compiler.compliance=1.8
 org.eclipse.jdt.core.compiler.debug.lineNumber=generate
 org.eclipse.jdt.core.compiler.debug.localVariable=generate
 org.eclipse.jdt.core.compiler.debug.sourceFile=generate
@@ -103,7 +103,7 @@ org.eclipse.jdt.core.compiler.problem.unusedPrivateMember=error
 org.eclipse.jdt.core.compiler.problem.unusedWarningToken=warning
 org.eclipse.jdt.core.compiler.problem.varargsArgumentNeedCast=warning
 org.eclipse.jdt.core.compiler.release=enabled
-org.eclipse.jdt.core.compiler.source=17
+org.eclipse.jdt.core.compiler.source=1.8
 org.eclipse.jdt.core.formatter.align_type_members_on_columns=false
 org.eclipse.jdt.core.formatter.alignment_for_additive_operator=16
 org.eclipse.jdt.core.formatter.alignment_for_arguments_in_allocation_expression=16

ui/org.eclipse.pde.junit.runtime/META-INF/MANIFEST.MF

@@ -2,16 +2,14 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.pde.junit.runtime; singleton:=true
-Bundle-Version: 3.7.200.qualifier
+Bundle-Version: 3.8.0.qualifier
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin
-Require-Bundle: org.eclipse.jdt.junit.runtime;bundle-version="[3.5.0,4.0.0)",
- org.junit;bundle-version="3.8.2",
- org.eclipse.core.runtime;bundle-version="[3.29.0,4.0.0)",
- org.eclipse.ui;bundle-version="[3.2.0,4.0.0)";resolution:=optional
+Require-Bundle: org.eclipse.jdt.junit.runtime;bundle-version="[3.4.0,4.0.0)",
+ org.eclipse.core.runtime;bundle-version="[3.7.0,4.0.0)",
+ org.eclipse.ui;bundle-version="[3.7.0,4.0.0)";resolution:=optional
 Export-Package: org.eclipse.pde.internal.junit.runtime;x-internal:=true
-Bundle-RequiredExecutionEnvironment: JavaSE-17
-Bundle-Activator: org.eclipse.pde.internal.junit.runtime.PDEJUnitRuntimePlugin
+Bundle-RequiredExecutionEnvironment: JavaSE-1.8
 Bundle-ActivationPolicy: lazy
 Import-Package: org.eclipse.ui.testing;resolution:=optional
 Automatic-Module-Name: org.eclipse.pde.junit.runtime

ui/org.eclipse.pde.junit.runtime/README.md

@@ -0,0 +1,18 @@
+This PDE JUnit runtime is added to test-runtimes launched from an Eclipse workspace and allows JUnit tests to be run with an OSGi runtime.
+It supports the following use cases:
+1. Headless tests (no UI, no workbench)<br/>
+  Runs NonUIThreadTestApplication with no testable object
+2. e4 UI tests (e4 UI, no workbench)<br/>
+  Runs NonUIThreadTestApplication with a testable object from e4 service
+3. UI tests run in the non UI thread (UI, workbench)<br/>
+  Runs NonUIThreadTestApplication with a testable object from e4 service or PlatformUI
+4. UI tests run in the UI thread (UI, workbench)<br/>
+  Runs UITestApplication with a testable object from e4 service or PlatformUI
+5. Headless tests with no application (no UI, no workbench, no application)<br/>
+  Runs directly with no application
+
+If no pde.junit.runtime is available in the Target-Platform the one from the running Eclipse is added to the test-runtime.
+Of course users can target older Eclipse versions (which for example require older Java-versions), 
+which is why the requirements of this Plug-in should be as low as possible to make it resolve even in older runtimes.
+
+If changes are made, one should ensure that the requirement's lower-bounds specified in the MANIFEST.MF are still valid.

ui/org.eclipse.pde.junit.runtime/src/org/eclipse/pde/internal/junit/runtime/MultiBundleClassLoader.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- *  Copyright (c) 2018 IBM Corporation and others.
+ *  Copyright (c) 2018, 2023 IBM Corporation and others.
  *
  *  This program and the accompanying materials
  *  are made available under the terms of the Eclipse Public License 2.0
@@ -36,8 +36,9 @@ protected Class<?> findClass(String name) throws ClassNotFoundException {
 		for (Bundle temp : bundleList) {
 			try {
 				Class<?> c = temp.loadClass(name);
-				if (c != null)
+				if (c != null) {
 					return c;
+				}
 			} catch (ClassNotFoundException e) {
 			}
 		}
@@ -46,9 +47,8 @@ protected Class<?> findClass(String name) throws ClassNotFoundException {
 
 	@Override
 	protected URL findResource(String name) {
-		URL url = null;
 		for (Bundle temp : bundleList) {
-			url = temp.getResource(name);
+			URL url = temp.getResource(name);
 			if (url != null) {
 				try {
 					return FileLocator.resolve(url);
@@ -57,7 +57,7 @@ protected URL findResource(String name) {
 				}
 			}
 		}
-		return url;
+		return null;
 	}
 
 	@Override

ui/org.eclipse.pde.junit.runtime/src/org/eclipse/pde/internal/junit/runtime/NonUIThreadTestApplication.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2009, 2015 EclipseSource Corporation and others.
+ * Copyright (c) 2009, 2023 EclipseSource Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -13,14 +13,19 @@
  *******************************************************************************/
 package org.eclipse.pde.internal.junit.runtime;
 
+import java.util.Objects;
+
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IExtension;
 import org.eclipse.core.runtime.IProduct;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.equinox.app.IApplication;
 import org.eclipse.equinox.app.IApplicationContext;
-import org.junit.Assert;
+import org.eclipse.ui.testing.TestableObject;
+import org.osgi.framework.BundleContext;
+import org.osgi.framework.FrameworkUtil;
+import org.osgi.framework.ServiceReference;
 
 /**
  * A Workbench that runs a test suite specified in the
@@ -32,27 +37,23 @@ public class NonUIThreadTestApplication implements IApplication {
 
 	protected IApplication fApplication;
 	protected Object fTestHarness;
+	protected boolean runInUIThreadAndRequirePlatformUI = false;
+	protected String defaultApplicationId = DEFAULT_HEADLESSAPP;
 
 	@Override
 	public Object start(IApplicationContext context) throws Exception {
 		String[] args = (String[]) context.getArguments().get(IApplicationContext.APPLICATION_ARGS);
 
 		String appId = getApplicationToRun(args);
-		IApplication app = getApplication(appId);
-		Assert.assertNotNull(app);
+		IApplication app = Objects.requireNonNull(getApplication(appId));
 
-		if (!DEFAULT_HEADLESSAPP.equals(appId)) {
+		if (runInUIThreadAndRequirePlatformUI || !DEFAULT_HEADLESSAPP.equals(appId)) {
 			// this means we are running a different application, which potentially can be UI application;
 			// non-ui thread test app can also mean we are running UI tests but outside the UI thread;
 			// this is a pattern used by SWT bot and worked before; we continue to support this
 			// (see bug 340906 for details)
 			installPlatformUITestHarness();
 		}
-
-		return runApp(app, context);
-	}
-
-	protected Object runApp(IApplication app, IApplicationContext context) throws Exception {
 		fApplication = app;
 		return fApplication.start(context);
 	}
@@ -66,27 +67,53 @@ protected Object runApp(IApplication app, IApplicationContext context) throws Ex
 	 *
 	 * @throws Exception
 	 */
-	private void installPlatformUITestHarness() throws Exception {
-		Object testableObject = PDEJUnitRuntimePlugin.getDefault().getTestableObject();
+	private void installPlatformUITestHarness() throws ReflectiveOperationException {
+		Object testableObject = getRegisteredTestableObject();
 		if (testableObject == null) {
-			try {
+			try { // If the service doesn't return a testable object ask PlatformUI directly
 				Class<?> platformUIClass = Class.forName("org.eclipse.ui.PlatformUI", true, getClass().getClassLoader()); //$NON-NLS-1$
 				testableObject = platformUIClass.getMethod("getTestableObject").invoke(null); //$NON-NLS-1$
-			} catch (ClassNotFoundException e) {
-				// PlatformUI is not available
+			} catch (ClassNotFoundException e) { // PlatformUI is not available
+				if (runInUIThreadAndRequirePlatformUI) {
+					throw e;
+				}
 			}
 		}
 		if (testableObject != null) {
-			fTestHarness = new PlatformUITestHarness(testableObject, true);
+			fTestHarness = new PlatformUITestHarness(testableObject, !runInUIThreadAndRequirePlatformUI);
+		}
+	}
+
+	/**
+	 * Returns a {@link TestableObject} provided by a TestableObject service or {@code null} if no implementation can be found.
+	 * The TestableObject is used to hook tests into the application lifecycle.
+	 * <p>
+	 * It is recommended the testable object is obtained via service instead Workbench#getWorkbenchTestable() to avoid
+	 * the tests having a dependency on the Workbench.
+	 * </p>
+	 * @return TestableObject provided via service or {@code null}
+	 */
+	private static Object getRegisteredTestableObject() {
+		BundleContext context = FrameworkUtil.getBundle(NonUIThreadTestApplication.class).getBundleContext();
+		ServiceReference<?> reference = context.getServiceReference("org.eclipse.ui.testing.TestableObject"); //$NON-NLS-1$
+		if (reference != null) {
+			try {
+				return context.getService(reference);
+			} finally {
+				context.ungetService(reference);
+			}
 		}
+		return null;
 	}
 
 	@Override
 	public void stop() {
-		if (fApplication != null)
+		if (fApplication != null) {
 			fApplication.stop();
-		if (fTestHarness != null)
+		}
+		if (fTestHarness != null) {
 			fTestHarness = null;
+		}
 	}
 
 	/*
@@ -98,8 +125,7 @@ private IApplication getApplication(String appId) throws CoreException {
 		// If no application is specified, the 3.0 default workbench application
 		// is returned.
 		IExtension extension = Platform.getExtensionRegistry().getExtension(Platform.PI_RUNTIME, Platform.PT_APPLICATIONS, appId);
-
-		Assert.assertNotNull(extension);
+		Objects.requireNonNull(extension);
 
 		// If the extension does not have the correct grammar, return null.
 		// Otherwise, return the application object.
@@ -108,8 +134,9 @@ private IApplication getApplication(String appId) throws CoreException {
 			IConfigurationElement[] runs = elements[0].getChildren("run"); //$NON-NLS-1$
 			if (runs.length > 0) {
 				Object runnable = runs[0].createExecutableExtension("class"); //$NON-NLS-1$
-				if (runnable instanceof IApplication)
+				if (runnable instanceof IApplication) {
 					return (IApplication) runnable;
+				}
 			}
 		}
 		return null;
@@ -125,18 +152,12 @@ private IApplication getApplication(String appId) throws CoreException {
 	 *
 	 */
 	private String getApplicationToRun(String[] args) {
-		for (int i = 0; i < args.length; i++) {
-			if (args[i].equals("-testApplication") && i < args.length - 1) //$NON-NLS-1$
-				return args[i + 1];
+		String testApp = RemotePluginTestRunner.getArgumentValue(args, "-testApplication"); //$NON-NLS-1$
+		if (testApp != null) {
+			return testApp;
 		}
 		IProduct product = Platform.getProduct();
-		if (product != null)
-			return product.getApplication();
-		return getDefaultApplicationId();
-	}
-
-	protected String getDefaultApplicationId() {
-		return DEFAULT_HEADLESSAPP;
+		return product != null ? product.getApplication() : defaultApplicationId;
 	}
 
 }