Add CSS selector integration tests for tab selection, .active class, and preference pseudo

tests/org.eclipse.e4.ui.tests.css.swt/src/org/eclipse/e4/ui/tests/css/swt/CTabFolderActiveClassTest.java

@@ -0,0 +1,99 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Lars Vogel 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:
+ *     Lars Vogel <Lars.Vogel@vogella.com> - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.e4.ui.tests.css.swt;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+
+import org.eclipse.e4.ui.css.swt.dom.WidgetElement;
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.custom.CTabFolder;
+import org.eclipse.swt.custom.CTabItem;
+import org.eclipse.swt.layout.FillLayout;
+import org.eclipse.swt.widgets.Shell;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Locks in how {@code CTabFolder.active { ... }} rules are matched based on
+ * the CSS class set via {@link WidgetElement#setCSSClass(org.eclipse.swt.widgets.Widget, String)}.
+ */
+public class CTabFolderActiveClassTest extends CSSSWTTestCase {
+
+	private Shell shell;
+
+	@Override
+	@AfterEach
+	public void tearDown() {
+		if (shell != null && !shell.isDisposed()) {
+			shell.dispose();
+			shell = null;
+		}
+		super.tearDown();
+	}
+
+	private CTabFolder createFolder() {
+		shell = new Shell(display, SWT.SHELL_TRIM);
+		shell.setLayout(new FillLayout());
+
+		CTabFolder folder = new CTabFolder(shell, SWT.NONE);
+		CTabItem item = new CTabItem(folder, SWT.NONE);
+		item.setText("Item 0");
+		folder.setSelection(0);
+		return folder;
+	}
+
+	@Test
+	void testActiveClassAppliesStyle() {
+		CTabFolder folder = createFolder();
+		WidgetElement.setCSSClass(folder, "active");
+
+		engine = createEngine("CTabFolder.active { background-color: #FF0000 }", display);
+		engine.applyStyles(shell, true);
+
+		assertEquals(RED, folder.getBackground().getRGB());
+	}
+
+	@Test
+	void testWithoutActiveClassRuleDoesNotApply() {
+		CTabFolder folder = createFolder();
+		// no setCSSClass call
+
+		engine = createEngine("CTabFolder.active { background-color: #FF0000 }", display);
+		engine.applyStyles(shell, true);
+
+		assertNotEquals(RED, folder.getBackground().getRGB());
+	}
+
+	@Test
+	void testClearingActiveClassDoesNotRevertBackground() {
+		CTabFolder folder = createFolder();
+		WidgetElement.setCSSClass(folder, "active");
+
+		engine = createEngine("CTabFolder.active { background-color: #FF0000 }", display);
+		engine.applyStyles(shell, true);
+		assertEquals(RED, folder.getBackground().getRGB());
+
+		// Surprise: clearing the CSS class and reapplying does NOT undo the
+		// previously painted background. Once CTabFolder#setBackground has
+		// been called by the handler, the folder retains that color even
+		// though the .active rule no longer matches. Pin this real engine
+		// behaviour so a future change that adds proper revert semantics
+		// shows up as a test failure.
+		WidgetElement.setCSSClass(folder, null);
+		engine.applyStyles(shell, true);
+
+		assertEquals(RED, folder.getBackground().getRGB());
+	}
+}

tests/org.eclipse.e4.ui.tests.css.swt/src/org/eclipse/e4/ui/tests/css/swt/CTabItemSelectionTest.java

@@ -0,0 +1,124 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Lars Vogel 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:
+ *     Lars Vogel <Lars.Vogel@vogella.com> - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.e4.ui.tests.css.swt;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.custom.CTabFolder;
+import org.eclipse.swt.custom.CTabItem;
+import org.eclipse.swt.graphics.RGB;
+import org.eclipse.swt.layout.FillLayout;
+import org.eclipse.swt.widgets.Event;
+import org.eclipse.swt.widgets.Shell;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Pins {@code CTabItem:selected} pseudo behaviour and the
+ * {@code CTabFolderElement} selection listener path.
+ */
+public class CTabItemSelectionTest extends CSSSWTTestCase {
+
+	private Shell shell;
+
+	@Override
+	@AfterEach
+	public void tearDown() {
+		if (shell != null && !shell.isDisposed()) {
+			shell.dispose();
+			shell = null;
+		}
+		super.tearDown();
+	}
+
+	private void spinEventLoop() {
+		// Drain queued SWT events. Same pattern as CTabItemTest.
+		for (int i = 0; i < 3; i++) {
+			while (display.readAndDispatch()) {
+			}
+			try {
+				Thread.sleep(10);
+			} catch (InterruptedException e) {
+			}
+		}
+	}
+
+	private CTabFolder createFolderWithTwoItems(String styleSheet) {
+		shell = new Shell(display, SWT.SHELL_TRIM);
+		shell.setLayout(new FillLayout());
+
+		CTabFolder folder = new CTabFolder(shell, SWT.NONE);
+		CTabItem item0 = new CTabItem(folder, SWT.NONE);
+		item0.setText("Item 0");
+		CTabItem item1 = new CTabItem(folder, SWT.NONE);
+		item1.setText("Item 1");
+		folder.setSelection(0);
+
+		engine = createEngine(styleSheet, display);
+		engine.applyStyles(shell, true);
+		shell.open();
+		return folder;
+	}
+
+	@Test
+	void testSelectedTabReceivesStyledSelectionForeground() {
+		// :selected for CTabItem maps to CTabFolder#getSelectionForeground(),
+		// not the per-item CTabItem#getForeground(). The matched declaration
+		// is intentionally observable on the parent folder.
+		CTabFolder folder = createFolderWithTwoItems("CTabItem:selected { color: #FF0000 }");
+		spinEventLoop();
+
+		assertEquals(RED, folder.getSelectionForeground().getRGB());
+	}
+
+	@Test
+	void testSelectionListenerReappliesStylesOnSelectionEvent() {
+		CTabFolder folder = createFolderWithTwoItems(
+				"CTabItem { color: #0000FF }\n" + "CTabItem:selected { color: #FF0000 }");
+		spinEventLoop();
+		assertEquals(RED, folder.getSelectionForeground().getRGB());
+
+		// Switch the selection. CTabFolder#setSelection on its own does not
+		// fire the SWT selection listener, so we explicitly dispatch the
+		// SWT.Selection event the way an end-user click would. This
+		// exercises CTabFolderElement#selectionListener which invokes
+		// applyStyles(folder, true) for us.
+		CTabItem item1 = folder.getItem(1);
+		folder.setSelection(item1);
+		Event event = new Event();
+		event.widget = folder;
+		event.item = item1;
+		folder.notifyListeners(SWT.Selection, event);
+		spinEventLoop();
+
+		// The folder's selection-foreground stays red because the rule still
+		// matches whichever item is currently selected.
+		assertEquals(RED, folder.getSelectionForeground().getRGB());
+		// Non-selected items inherit the plain CTabItem rule.
+		assertEquals(new RGB(0, 0, 255), folder.getForeground().getRGB());
+	}
+
+	@Test
+	void testNonSelectedRuleColorIsNotRed() {
+		CTabFolder folder = createFolderWithTwoItems(
+				"CTabItem { color: #0000FF }\n" + "CTabItem:selected { color: #FF0000 }");
+		spinEventLoop();
+
+		// The non-selected foreground (plain CTabItem rule) is blue, not red.
+		assertNotEquals(RED, folder.getForeground().getRGB());
+		assertEquals(new RGB(0, 0, 255), folder.getForeground().getRGB());
+	}
+}

tests/org.eclipse.e4.ui.tests.css.swt/src/org/eclipse/e4/ui/tests/css/swt/IEclipsePreferencesPseudoKeyTest.java

@@ -0,0 +1,87 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Lars Vogel 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:
+ *     Lars Vogel <Lars.Vogel@vogella.com> - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.e4.ui.tests.css.swt;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.eclipse.core.internal.preferences.EclipsePreferences;
+import org.eclipse.core.runtime.preferences.IEclipsePreferences;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Locks in the {@code IEclipsePreferences#node:pseudo} selector form used by
+ * shipped themes. See Bug 466075.
+ */
+public class IEclipsePreferencesPseudoKeyTest extends CSSSWTTestCase {
+
+	@Test
+	void testPseudoSelectorMatchesAndWritesPreferenceValue() {
+		IEclipsePreferences preferences = new EclipsePreferences(null, "org.eclipse.jdt.ui") {};
+
+		engine = createEngine(
+				"""
+					IEclipsePreferences#org-eclipse-jdt-ui:org-eclipse-ui-themes {\
+					preferences: 'semanticHighlighting.abstractClass.color=128,255,0'\
+					}""",
+				display);
+		engine.applyStyles(preferences, false);
+
+		// Bug 466075
+		assertEquals("128,255,0", preferences.get("semanticHighlighting.abstractClass.color", null));
+	}
+
+	@Test
+	void testDifferentPseudosOnSameNodeAllContribute() {
+		// Mirrors how org.eclipse.ui.editors and org.eclipse.ui.themes both
+		// contribute to the same preference node via different pseudo tags.
+		IEclipsePreferences preferences = new EclipsePreferences(null, "org.eclipse.ui.workbench") {};
+
+		engine = createEngine(
+				"""
+					IEclipsePreferences#org-eclipse-ui-workbench:org-eclipse-ui-editors {\
+					preferences: 'org.eclipse.ui.editors.inlineAnnotationColor=155,155,155'\
+					}\
+					IEclipsePreferences#org-eclipse-ui-workbench:org-eclipse-ui-themes {\
+					preferences: 'ERROR_COLOR=247,68,117'\
+					}""",
+				display);
+		engine.applyStyles(preferences, false);
+
+		assertEquals("155,155,155", preferences.get("org.eclipse.ui.editors.inlineAnnotationColor", null));
+		assertEquals("247,68,117", preferences.get("ERROR_COLOR", null));
+	}
+
+	@Test
+	void testCascadeOverrideForSameKeyAndSamePseudoLastWins() {
+		// Two equal-specificity rules under the same pseudo write the same
+		// preference key with different values. The CSS cascade in viewCSS
+		// resolves the duplicate "preferences" property to the second rule's
+		// value before EclipsePreferencesHandler ever sees it, so the LATER
+		// rule wins. This matches standard CSS source-order tiebreak.
+		IEclipsePreferences preferences = new EclipsePreferences(null, "org.eclipse.jdt.ui") {};
+
+		engine = createEngine(
+				"""
+					IEclipsePreferences#org-eclipse-jdt-ui:org-eclipse-ui-themes {\
+					preferences: 'semanticHighlighting.abstractClass.color=128,255,0'\
+					}\
+					IEclipsePreferences#org-eclipse-jdt-ui:org-eclipse-ui-themes {\
+					preferences: 'semanticHighlighting.abstractClass.color=255,0,0'\
+					}""",
+				display);
+		engine.applyStyles(preferences, false);
+
+		assertEquals("255,0,0", preferences.get("semanticHighlighting.abstractClass.color", null));
+	}
+}