Migrate org.eclipse.ui.tests.navigator from JUnit 4 to JUnit 5

This commit migrates the entire org.eclipse.ui.tests.navigator test suite
from JUnit 4 to JUnit 5, modernizing the test infrastructure and improving
test reliability with better resource management.

JUnit 5 Migration Changes:
- Updated all test annotations (@before → @beforeeach, @after → @AfterEach,
  @ignore → @disabled)
- Migrated static imports from org.junit.Assert to
  org.junit.jupiter.api.Assertions
- Fixed all assertion parameter orders from JUnit 4 style (message-first) to
  JUnit 5 style (message-last):
  * assertEquals(message, expected, actual) → assertEquals(expected, actual, message)
  * assertTrue(message, condition) → assertTrue(condition, message)
  * assertFalse(message, condition) → assertFalse(condition, message)

Test Infrastructure Improvements:
- Added CloseTestWindowsExtension: A new JUnit 5 extension that automatically
  manages UI test windows and shell cleanup, replacing the previous JUnit 4
  rule-based approach
- Updated GoBackForwardsTest to use @RegisterExtension with the new extension
- Ensures better test isolation by cleaning up leaked shells between tests

Files Modified (32):
- ActionProviderTest.java
- ActivityTest.java
- CloseTestWindowsExtension.java (new)
- DecorationSchedulerRaceConditionTest.java
- DnDTest.java
- EvaluationCacheTest.java
- ExtensionsTest.java
- FilterTest.java
- FirstClassM1Tests.java
- GoBackForwardsTest.java
- INavigatorContentServiceTests.java
- InitialActivationTest.java
- LabelProviderTest.java
- LinkHelperTest.java
- M12Tests.java
- NavigatorTestBase.java
- OpenTest.java
- PerformanceTest.java
- PipelineChainTest.java
- PipelineTest.java
- ProgrammaticOpenTest.java
- ResourceTransferTest.java
- ShowInTest.java
- SorterTest.java
- ViewerTest.java
- WorkingSetTest.java
- cdt/CdtTest.java
- jst/JstPipelineTest.java
- resources/FoldersAsProjectsContributionTest.java
- resources/NestedResourcesTests.java
- resources/PathComparatorTest.java
- resources/ResourceMgmtActionProviderTests.java

Benefits:
- Uses modern JUnit 5 features and best practices
- Improved resource cleanup prevents test interference
- Consistent with Eclipse platform's migration to JUnit 5
- Better test isolation and reliability

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: vogella

tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/ActionProviderTest.java

@@ -14,9 +14,9 @@
  *******************************************************************************/
 package org.eclipse.ui.tests.navigator;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -33,7 +33,7 @@
 import org.eclipse.ui.tests.harness.util.DisplayHelper;
 import org.eclipse.ui.tests.navigator.extension.TestContentProvider;
 import org.eclipse.ui.tests.navigator.extension.TestExtensionTreeData;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 public class ActionProviderTest extends NavigatorTestBase {
 

tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/ActivityTest.java

@@ -15,8 +15,8 @@
  *******************************************************************************/
 package org.eclipse.ui.tests.navigator;
 
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.HashSet;
 import java.util.Set;
@@ -25,7 +25,7 @@
 import org.eclipse.jface.viewers.StructuredSelection;
 import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.activities.IWorkbenchActivitySupport;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 public class ActivityTest extends NavigatorTestBase {
 

tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/CloseTestWindowsExtension.java

@@ -0,0 +1,142 @@
+/*******************************************************************************
+ * Copyright (c) 2025 IBM Corporation and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+
+package org.eclipse.ui.tests.navigator;
+
+import static org.eclipse.ui.tests.harness.util.UITestUtil.processEvents;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+
+import org.eclipse.swt.widgets.Shell;
+import org.eclipse.ui.IWindowListener;
+import org.eclipse.ui.IWorkbenchWindow;
+import org.eclipse.ui.PlatformUI;
+import org.junit.jupiter.api.extension.AfterEachCallback;
+import org.junit.jupiter.api.extension.BeforeEachCallback;
+import org.junit.jupiter.api.extension.ExtensionContext;
+
+/**
+ * JUnit 5 Extension for UI tests to clean up windows/shells:
+ * <ul>
+ * <li>prints the test name to the log before and after each test case
+ * <li>closes windows opened during the test case
+ * <li>checks for shells unintentionally leaked from the test case
+ * </ul>
+ */
+public class CloseTestWindowsExtension implements BeforeEachCallback, AfterEachCallback {
+
+	private String testName;
+	private final List<IWorkbenchWindow> testWindows = new ArrayList<>(3);
+	private TestWindowListener windowListener;
+	private Set<Shell> initialShells;
+	private boolean leakChecksDisabled;
+
+	@Override
+	public void beforeEach(ExtensionContext context) throws Exception {
+		this.testName = context.getDisplayName();
+		addWindowListener();
+		storeInitialShells();
+		trace(formatTestStartMessage(testName));
+	}
+
+	@Override
+	public void afterEach(ExtensionContext context) throws Exception {
+		trace(formatTestFinishedMessage(testName));
+		removeWindowListener();
+		processEvents();
+		closeAllTestWindows();
+		processEvents();
+		checkForLeakedShells();
+	}
+
+	private static void trace(String msg) {
+		System.out.println(msg);
+	}
+
+	private void addWindowListener() {
+		windowListener = new TestWindowListener();
+		PlatformUI.getWorkbench().addWindowListener(windowListener);
+	}
+
+	private void removeWindowListener() {
+		if (windowListener != null) {
+			PlatformUI.getWorkbench().removeWindowListener(windowListener);
+		}
+	}
+
+	private void closeAllTestWindows() {
+		List<IWorkbenchWindow> testWindowsCopy = new ArrayList<>(testWindows);
+		for (IWorkbenchWindow testWindow : testWindowsCopy) {
+			testWindow.close();
+		}
+		testWindows.clear();
+	}
+
+	private class TestWindowListener implements IWindowListener {
+		@Override
+		public void windowActivated(IWorkbenchWindow window) {
+			// do nothing
+		}
+
+		@Override
+		public void windowDeactivated(IWorkbenchWindow window) {
+			// do nothing
+		}
+
+		@Override
+		public void windowClosed(IWorkbenchWindow window) {
+			testWindows.remove(window);
+		}
+
+		@Override
+		public void windowOpened(IWorkbenchWindow window) {
+			testWindows.add(window);
+		}
+	}
+
+	private void storeInitialShells() {
+		this.initialShells = Set.of(PlatformUI.getWorkbench().getDisplay().getShells());
+	}
+
+	private void checkForLeakedShells() {
+		List<String> leakedModalShellTitles = new ArrayList<>();
+		Shell[] shells = PlatformUI.getWorkbench().getDisplay().getShells();
+		for (Shell shell : shells) {
+			if (!shell.isDisposed() && !initialShells.contains(shell)) {
+				leakedModalShellTitles.add(shell.getText());
+				shell.close();
+			}
+		}
+		if (!leakChecksDisabled) {
+			assertEquals(0, leakedModalShellTitles.size(),
+					"Test leaked modal shell: [" + String.join(", ", leakedModalShellTitles) + "]");
+		}
+	}
+
+	public void disableLeakChecks() {
+		this.leakChecksDisabled = true;
+	}
+
+	private static String formatTestStartMessage(String testName) {
+		return "----- " + testName + System.lineSeparator() + testName + ": setUp...";
+	}
+
+	private static String formatTestFinishedMessage(String testName) {
+		return testName + ": tearDown...\n";
+	}
+
+}

tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/DecorationSchedulerRaceConditionTest.java

@@ -13,7 +13,7 @@
  *******************************************************************************/
 package org.eclipse.ui.tests.navigator;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import java.util.concurrent.Semaphore;
 
@@ -32,9 +32,9 @@
 import org.eclipse.ui.tests.harness.util.DisplayHelper;
 import org.eclipse.ui.tests.navigator.extension.DecorationSchedulerRaceConditionTestDecorator;
 import org.eclipse.ui.tests.navigator.util.TestWorkspace;
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
 /**
  * @since 3.3
@@ -79,7 +79,7 @@ public DecorationSchedulerRaceConditionTest() {
 	}
 
 	@Override
-	@Before
+	@BeforeEach
 	public void setUp() throws CoreException {
 		super.setUp();
 
@@ -102,7 +102,7 @@ public void setUp() throws CoreException {
 		assertEquals(TestWorkspace.P1_PROJECT_NAME + DECORATION_TEXT_1, rootItems[0].getText());
 	}
 
-	@After
+	@AfterEach
 	public void resetDecoratorEnablement() throws CoreException {
 		IDecoratorManager manager = PlatformUI.getWorkbench().getDecoratorManager();
 		manager.setEnabled("org.eclipse.ui.tests.navigator.bug417255Decorator", false);

tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/DnDTest.java

@@ -14,10 +14,10 @@
  *******************************************************************************/
 package org.eclipse.ui.tests.navigator;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.eclipse.core.resources.IFile;
 import org.eclipse.jface.viewers.StructuredSelection;
@@ -31,7 +31,7 @@
 import org.eclipse.ui.tests.harness.util.DisplayHelper;
 import org.eclipse.ui.tests.harness.util.SWTEventHelper;
 import org.eclipse.ui.tests.navigator.extension.TestDragAssistant;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 public class DnDTest extends NavigatorTestBase {
 

tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/EvaluationCacheTest.java

@@ -23,8 +23,8 @@
 import org.eclipse.ui.navigator.INavigatorViewerDescriptor;
 import org.eclipse.ui.tests.navigator.util.TestNavigatorActivationService;
 import org.eclipse.ui.tests.navigator.util.TestNavigatorViewerDescriptor;
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests the {@link EvaluationCache} to ensure it can find various key types as
@@ -51,9 +51,9 @@ private void doSimpleAddGet(boolean toComputeOverrides) {
 		Object key = new Object();
 		NavigatorContentDescriptor[] value = new NavigatorContentDescriptor[0];
 		cache.setDescriptors(key, value, toComputeOverrides);
-		Assert.assertSame(value, cache.getDescriptors(key, toComputeOverrides));
+		Assertions.assertSame(value, cache.getDescriptors(key, toComputeOverrides));
 		// The other "half" of the cache should not have this.
-		Assert.assertNull(cache.getDescriptors(key, !toComputeOverrides));
+		Assertions.assertNull(cache.getDescriptors(key, !toComputeOverrides));
 	}
 
 	@Test
@@ -76,10 +76,10 @@ private void doNotSameInstEqual(boolean toComputeOverrides) {
 		// Equal thing but different instance should still be equal.
 		java.util.List key2 = new ArrayList<>(key);
 		// Should also find it under this new, equal key.
-		Assert.assertSame(value, cache.getDescriptors(key2, toComputeOverrides));
+		Assertions.assertSame(value, cache.getDescriptors(key2, toComputeOverrides));
 		// The other "half" of the cache should not have this for either key.
-		Assert.assertNull(cache.getDescriptors(key, !toComputeOverrides));
-		Assert.assertNull(cache.getDescriptors(key2, !toComputeOverrides));
+		Assertions.assertNull(cache.getDescriptors(key, !toComputeOverrides));
+		Assertions.assertNull(cache.getDescriptors(key2, !toComputeOverrides));
 	}
 
 	@Test
@@ -96,10 +96,10 @@ private void doTestReplace(boolean toComputeOverrides) {
 		Object key = new Object();
 		NavigatorContentDescriptor[] value1 = new NavigatorContentDescriptor[0];
 		cache.setDescriptors(key, value1, toComputeOverrides);
-		Assert.assertSame(value1, cache.getDescriptors(key, toComputeOverrides));
+		Assertions.assertSame(value1, cache.getDescriptors(key, toComputeOverrides));
 		NavigatorContentDescriptor[] value2 = new NavigatorContentDescriptor[0];
 		cache.setDescriptors(key, value2, toComputeOverrides);
-		Assert.assertSame(value2, cache.getDescriptors(key, toComputeOverrides));
+		Assertions.assertSame(value2, cache.getDescriptors(key, toComputeOverrides));
 	}
 
 	@Test
@@ -118,14 +118,14 @@ public void testOnVisibilityOrActivationChangeClearsCaches() {
 		NavigatorContentDescriptor[] value1 = new NavigatorContentDescriptor[0];
 		cache.setDescriptors(key, value1, false);
 		// Make sure they actually got inserted.
-		Assert.assertSame(value1, cache.getDescriptors(key, false));
+		Assertions.assertSame(value1, cache.getDescriptors(key, false));
 		NavigatorContentDescriptor[] value2 = new NavigatorContentDescriptor[0];
 		cache.setDescriptors(key, value2, true);
-		Assert.assertSame(value2, cache.getDescriptors(key, true));
+		Assertions.assertSame(value2, cache.getDescriptors(key, true));
 		cache.onVisibilityOrActivationChange();
 		// Now trying to find them should give null (non present).
-		Assert.assertNull(cache.getDescriptors(key, false));
-		Assert.assertNull(cache.getDescriptors(key, true));
+		Assertions.assertNull(cache.getDescriptors(key, false));
+		Assertions.assertNull(cache.getDescriptors(key, true));
 	}
 
 	// TODO Some way to reliably test the clearing of entries. Possibly using

tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/ExtensionsTest.java

@@ -15,13 +15,13 @@
  *******************************************************************************/
 package org.eclipse.ui.tests.navigator;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.ui.internal.navigator.filters.CommonFilterSelectionDialog;
 import org.eclipse.ui.navigator.CommonViewer;
 import org.eclipse.ui.tests.harness.util.DisplayHelper;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 public class ExtensionsTest extends NavigatorTestBase {
 

tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/FilterTest.java

@@ -15,13 +15,13 @@
  *******************************************************************************/
 package org.eclipse.ui.tests.navigator;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.eclipse.swt.widgets.TreeItem;
 import org.eclipse.ui.internal.navigator.NavigatorContentService;
 import org.eclipse.ui.internal.navigator.NavigatorFilterService;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 public class FilterTest extends NavigatorTestBase {
 

tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/FirstClassM1Tests.java

@@ -15,11 +15,11 @@
 
 package org.eclipse.ui.tests.navigator;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import org.eclipse.swt.widgets.TreeItem;
 import org.eclipse.ui.tests.navigator.m12.model.M1Project;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * M1/M2 tests with M1 as a first class provider (i.e. override policy set to