Remove type hierarchy of Win32AutoscaleTestBase

Auto-scale related, Windows-specific tests are currently organized in a
class hierarchy based on Win32AutoscaleTestBase. This leads to
unnecessarily initialized objects (e.g., shells or displays without any
need for a test) and the strict necessity to use activated
monitor-specific scaling in actual tests or to revert the setup logic
affecting that value by hand.

This change removes the Win32AutoscaleTestBase and moves the common test
functionality into extensions (PlatformSpecificExecution,
ResetMonitorSpecificScaling and WithMonitorSpecificScaling) as well as
the utility class DPITestUtil.

Author: HeikoKlare

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/graphics/GCWin32Tests.java

@@ -20,12 +20,18 @@
 
 import org.eclipse.swt.*;
 import org.eclipse.swt.internal.*;
+import org.eclipse.swt.widgets.*;
 import org.junit.jupiter.api.*;
+import org.junit.jupiter.api.extension.*;
 
-class GCWin32Tests extends Win32AutoscaleTestBase {
+@ExtendWith(PlatformSpecificExecutionExtension.class)
+@ExtendWith(WithMonitorSpecificScalingExtension.class)
+class GCWin32Tests {
 
 	@Test
 	public void gcZoomLevelMustChangeOnShellZoomChange() {
+		Shell shell = new Shell(Display.getDefault());
+
 		CompletableFuture<Integer> gcNativeZoom = new CompletableFuture<>();
 		CompletableFuture<Integer> scaledGcNativeZoom = new CompletableFuture<>();
 		int zoom = DPIUtil.getDeviceZoom();
@@ -42,7 +48,7 @@ public void gcZoomLevelMustChangeOnShellZoomChange() {
 		assertEquals("GCData must have a zoom level equal to the actual zoom level of the widget/shell", DPIUtil.getNativeDeviceZoom(), (int) gcNativeZoom.join());
 
 		int newSWTZoom = zoom * 2;
-		changeDPIZoom(newSWTZoom);
+		DPITestUtil.changeDPIZoom(shell, newSWTZoom);
 		isScaled.set(true);
 		shell.setVisible(false);
 		shell.setVisible(true);
@@ -52,6 +58,8 @@ public void gcZoomLevelMustChangeOnShellZoomChange() {
 
 	@Test
 	public void drawnElementsShouldScaleUpToTheRightZoomLevel() {
+		Shell shell = new Shell(Display.getDefault());
+
 		int zoom = DPIUtil.getDeviceZoom();
 		int scalingFactor = 2;
 		GC gc = GC.win32_new(shell, new GCData());

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/graphics/PathWin32Tests.java

@@ -19,15 +19,20 @@
 
 import org.eclipse.swt.internal.*;
 import org.eclipse.swt.internal.gdip.*;
+import org.eclipse.swt.widgets.*;
 import org.junit.jupiter.api.*;
+import org.junit.jupiter.api.extension.*;
 
-class PathWin32Tests extends Win32AutoscaleTestBase {
+@ExtendWith(PlatformSpecificExecutionExtension.class)
+@ExtendWith(WithMonitorSpecificScalingExtension.class)
+class PathWin32Tests {
 
 	int zoom = 100;
 	int scaledZoom = 200;
 
 	@Test
 	public void testPathMustBeScaledOnZoomLevelChange() {
+		Display display = Display.getDefault();
 		Path path = new Path(display);
 		path.addArc(0, 0, 10, 10, 0, 90);
 		PathData pathData = path.getPathData();
@@ -40,6 +45,7 @@ public void testPathMustBeScaledOnZoomLevelChange() {
 
 	@Test
 	public void testHandlesExistForEachZoomLevelInHashMap() {
+		Display display = Display.getDefault();
 		DPIUtil.setDeviceZoom(zoom);
 		Path path = new Path(display);
 		path.addArc(0, 0, 10, 10, 0, 90);
@@ -50,6 +56,7 @@ public void testHandlesExistForEachZoomLevelInHashMap() {
 
 	@Test
 	public void testBoundsAreScaledWRTZoomLevel() {
+		Display display = Display.getDefault();
 		DPIUtil.setDeviceZoom(zoom);
 		int scalingFactor = scaledZoom/zoom;
 		Path path = new Path(display);

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/graphics/RegionWin32Tests.java

@@ -17,12 +17,18 @@
 
 import org.eclipse.swt.internal.*;
 import org.eclipse.swt.internal.win32.*;
+import org.eclipse.swt.widgets.*;
 import org.junit.jupiter.api.*;
+import org.junit.jupiter.api.extension.*;
 
-class RegionWin32Tests extends Win32AutoscaleTestBase {
+@ExtendWith(PlatformSpecificExecutionExtension.class)
+@ExtendWith(WithMonitorSpecificScalingExtension.class)
+class RegionWin32Tests {
 
 	@Test
 	public void testRegionMustBeScaledOnHandleOfScaledZoomLevel() {
+		Display display = Display.getDefault();
+
 		int zoom = DPIUtil.getDeviceZoom();
 		int scalingFactor = 2;
 

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/graphics/TextLayoutWin32Tests.java

@@ -17,13 +17,19 @@
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
 
 import org.eclipse.swt.internal.*;
+import org.eclipse.swt.widgets.*;
 import org.junit.jupiter.api.*;
+import org.junit.jupiter.api.extension.*;
 
-class TextLayoutWin32Tests extends Win32AutoscaleTestBase {
+@ExtendWith(PlatformSpecificExecutionExtension.class)
+@ExtendWith(WithMonitorSpecificScalingExtension.class)
+class TextLayoutWin32Tests {
 	final static String text = "This is a text for testing.";
 
 	@Test
 	public void testGetBoundPublicAPIshouldReturnTheSameValueRegardlessOfZoomLevel() {
+		Display display = Display.getDefault();
+
 		final TextLayout layout = new TextLayout(display);
 		GCData unscaledData = new GCData();
 		unscaledData.nativeZoom = DPIUtil.getNativeDeviceZoom();
@@ -44,14 +50,17 @@ public void testGetBoundPublicAPIshouldReturnTheSameValueRegardlessOfZoomLevel()
 
 	@Test
 	public void testCalculateGetBoundsWithVerticalIndent() {
+		Display display = Display.getDefault();
+		Shell shell = new Shell(display);
+
 		TextLayout layout = new TextLayout(display);
 		layout.setVerticalIndent(16);
 		layout.setText(text);
 		Rectangle unscaledBounds = layout.getBounds();
 
 		int scalingFactor = 2;
 		int newZoom = DPIUtil.getNativeDeviceZoom() * scalingFactor;
-		changeDPIZoom(newZoom);
+		DPITestUtil.changeDPIZoom(shell, newZoom);
 		TextLayout scaledLayout = new TextLayout(display);
 		scaledLayout.setVerticalIndent(16);
 		scaledLayout.setText(text);

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/graphics/TransformWin32Tests.java

@@ -18,12 +18,17 @@
 
 import org.eclipse.swt.internal.*;
 import org.eclipse.swt.internal.gdip.*;
+import org.eclipse.swt.widgets.*;
 import org.junit.jupiter.api.*;
+import org.junit.jupiter.api.extension.*;
 
-class TransformWin32Tests extends Win32AutoscaleTestBase {
+@ExtendWith(PlatformSpecificExecutionExtension.class)
+@ExtendWith(WithMonitorSpecificScalingExtension.class)
+class TransformWin32Tests {
 
 	@Test
 	public void testShouldHaveDifferentHandlesAtDifferentZoomLevels() {
+		Display display = Display.getDefault();
 		int zoom = DPIUtil.getDeviceZoom();
 		Transform transform = new Transform(display);
 		long scaledHandle = transform.getHandle(zoom * 2);
@@ -34,6 +39,7 @@ public void testShouldHaveDifferentHandlesAtDifferentZoomLevels() {
 
 	@Test
 	public void testScaledTrasformMustHaveScaledValues() {
+		Display display = Display.getDefault();
 		int zoom = DPIUtil.getDeviceZoom();
 		Transform transform = new Transform(display, 0, 0, 0, 0, 4, 2);
 		float[] elements = new float[6];

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/internal/Win32AutoscaleTestBase.java renamed to bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/internal/DPITestUtil.java

@@ -14,35 +14,16 @@
 package org.eclipse.swt.internal;
 
 import org.eclipse.swt.widgets.*;
-import org.junit.jupiter.api.*;
 
-public abstract class Win32AutoscaleTestBase {
-	protected Display display;
-	protected Shell shell;
+public final class DPITestUtil {
 
-	@BeforeAll
-	public static void assumeIsFittingPlatform() {
-		PlatformSpecificExecution.assumeIsFittingPlatform();
+	private DPITestUtil() {
 	}
 
-	@BeforeEach
-	public void setUpTest() {
-		display = Display.getDefault();
-		display.setRescalingAtRuntime(true);
-		shell = new Shell(display);
-	}
-
-	@AfterEach
-	public void tearDownTest() {
-		if (shell != null) {
-			shell.dispose();
-		}
-		display.dispose();
-	}
-
-	protected void changeDPIZoom (int nativeZoom) {
+	public static void changeDPIZoom (Shell shell, int nativeZoom) {
 		DPIUtil.setDeviceZoom(nativeZoom);
 		float scalingFactor = 1f * DPIUtil.getZoomForAutoscaleProperty(nativeZoom) / DPIUtil.getZoomForAutoscaleProperty(shell.nativeZoom);
 		DPIZoomChangeRegistry.applyChange(shell, nativeZoom, scalingFactor);
 	}
-}
+
+}

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/internal/DefaultSWTFontRegistryTests.java

@@ -20,17 +20,14 @@
 import org.eclipse.swt.graphics.*;
 import org.eclipse.swt.widgets.*;
 import org.junit.jupiter.api.*;
+import org.junit.jupiter.api.extension.*;
 
+@ExtendWith(PlatformSpecificExecutionExtension.class)
 class DefaultSWTFontRegistryTests {
 	private static String TEST_FONT = "Helvetica";
 	private Display display;
 	private SWTFontRegistry fontRegistry;
 
-	@BeforeAll
-	public static void assumeIsFittingPlatform() {
-		PlatformSpecificExecution.assumeIsFittingPlatform();
-	}
-
 	@BeforeEach
 	public void setUp() {
 		this.display = Display.getDefault();
@@ -42,6 +39,7 @@ public void tearDown() {
 		if (this.fontRegistry != null) {
 			this.fontRegistry.dispose();
 		}
+		display.dispose();
 	}
 
 	@Test

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/internal/PlatformSpecificExecution.java renamed to bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/internal/PlatformSpecificExecutionExtension.java

@@ -14,11 +14,14 @@
 
 import java.net.*;
 
-public final class PlatformSpecificExecution {
-	private PlatformSpecificExecution()  {
+import org.junit.jupiter.api.extension.*;
+
+public final class PlatformSpecificExecutionExtension implements BeforeAllCallback {
+	private PlatformSpecificExecutionExtension()  {
 	}
 
-	public static void assumeIsFittingPlatform() {
+	@Override
+	public void beforeAll(ExtensionContext context) throws Exception {
 		assumeTrue("test is specific for Windows", isFittingOS());
 		assumeTrue("architecture of platform does not match", isFittingArchitecture());
 	}
@@ -28,7 +31,7 @@ private static boolean isFittingOS() {
 	}
 
 	private static boolean isFittingArchitecture() {
-		Class<?> thisClass = PlatformSpecificExecution.class;
+		Class<?> thisClass = PlatformSpecificExecutionExtension.class;
 		String thisClassResourcePath = thisClass.getName().replace('.', '/')  + ".class";
 		URL thisClassURL = thisClass.getClassLoader().getResource(thisClassResourcePath); //$NON-NLS-1$
 		return thisClassURL.toString().contains(Library.arch());

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/internal/ResetMonitorSpecificScalingExtension.java

@@ -0,0 +1,38 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Vector Informatik GmbH
+ *
+ * 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
+ *******************************************************************************/
+package org.eclipse.swt.internal;
+
+import org.eclipse.swt.widgets.*;
+import org.junit.jupiter.api.extension.*;
+
+/**
+ * Resets the monitor-specific scaling configuration after the test has been executed.
+ * Disposes the default display before and after test execution.
+ */
+public sealed class ResetMonitorSpecificScalingExtension implements BeforeEachCallback, AfterEachCallback permits WithMonitorSpecificScalingExtension {
+	private boolean wasMonitorSpecificScalingActive;
+
+	protected ResetMonitorSpecificScalingExtension() {
+	}
+
+	@Override
+	public void beforeEach(ExtensionContext context) throws Exception {
+		wasMonitorSpecificScalingActive = DPIUtil.isMonitorSpecificScalingActive();
+		Display.getDefault().dispose();
+	}
+
+	@Override
+	public void afterEach(ExtensionContext context) throws Exception {
+		DPIUtil.setMonitorSpecificScaling(wasMonitorSpecificScalingActive);
+		Display.getDefault().dispose();
+	}
+
+}

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/internal/ScalingSWTFontRegistryTests.java

@@ -19,16 +19,13 @@
 import org.eclipse.swt.graphics.*;
 import org.eclipse.swt.widgets.*;
 import org.junit.jupiter.api.*;
+import org.junit.jupiter.api.extension.*;
 
+@ExtendWith(PlatformSpecificExecutionExtension.class)
 class ScalingSWTFontRegistryTests {
 	private static String TEST_FONT = "Helvetica";
 	private SWTFontRegistry fontRegistry;
 
-	@BeforeAll
-	public static void assumeIsFittingPlatform() {
-		PlatformSpecificExecution.assumeIsFittingPlatform();
-	}
-
 	@BeforeEach
 	public void setUp() {
 		this.fontRegistry = new ScalingSWTFontRegistry(Display.getDefault());

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/internal/WithMonitorSpecificScalingExtension.java

@@ -0,0 +1,30 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Vector Informatik GmbH
+ *
+ * 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
+ *******************************************************************************/
+package org.eclipse.swt.internal;
+
+import org.junit.jupiter.api.extension.*;
+
+/**
+ * Runs a test with monitor specific scaling. Disposes the default display before and after execution.
+ */
+public final class WithMonitorSpecificScalingExtension extends ResetMonitorSpecificScalingExtension {
+
+	private WithMonitorSpecificScalingExtension() {
+		super();
+	}
+
+	@Override
+	public void beforeEach(ExtensionContext context) throws Exception {
+		super.beforeEach(context);
+		DPIUtil.setMonitorSpecificScaling(true);
+	}
+
+}