fix CodeMiningLineHeaderAnnotation#getMultilineHeight

it should never return 0. Fix race condition when code minings are not
yet available.
#2786

Author: tobias-melcher

bundles/org.eclipse.jface.text/src/org/eclipse/jface/internal/text/codemining/CodeMiningLineHeaderAnnotation.java

@@ -121,6 +121,9 @@ private int getMultilineHeight(GC gc) {
 			}
 			ignoreFirstLine= true;
 		}
+		if (sumLineHeight == 0) {
+			return super.getHeight();
+		}
 		if (gc != null) {
 			return sumLineHeight;
 		} else {

tests/org.eclipse.jface.text.tests/src/org/eclipse/jface/text/tests/JFaceTextTestSuite.java

@@ -17,6 +17,7 @@
 import org.junit.runners.Suite;
 import org.junit.runners.Suite.SuiteClasses;
 
+import org.eclipse.jface.text.tests.codemining.CodeMiningLineHeaderAnnotationTest;
 import org.eclipse.jface.text.tests.codemining.CodeMiningProjectionViewerTest;
 import org.eclipse.jface.text.tests.codemining.CodeMiningTest;
 import org.eclipse.jface.text.tests.contentassist.AsyncContentAssistTest;
@@ -72,6 +73,7 @@
 		LineContentBoundsDrawingTest.class,
 		AnnotationOnTabTest.class,
 		CodeMiningTest.class,
+		CodeMiningLineHeaderAnnotationTest.class,
 		CodeMiningProjectionViewerTest.class,
 
 		TabsToSpacesConverterTest.class,

tests/org.eclipse.jface.text.tests/src/org/eclipse/jface/text/tests/codemining/CodeMiningLineHeaderAnnotationTest.java

@@ -0,0 +1,91 @@
+/*******************************************************************************
+ * Copyright (c) 2025 SAP SE
+ *
+ * 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.jface.text.tests.codemining;
+
+import static org.junit.Assert.assertNotEquals;
+
+import java.util.Arrays;
+
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.custom.StyledText;
+import org.eclipse.swt.layout.FillLayout;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Shell;
+
+import org.eclipse.jface.internal.text.codemining.CodeMiningLineHeaderAnnotation;
+
+import org.eclipse.jface.text.Document;
+import org.eclipse.jface.text.Position;
+import org.eclipse.jface.text.codemining.LineHeaderCodeMining;
+import org.eclipse.jface.text.source.AnnotationModel;
+import org.eclipse.jface.text.source.AnnotationPainter;
+import org.eclipse.jface.text.source.SourceViewer;
+import org.eclipse.jface.text.source.inlined.AbstractInlinedAnnotation;
+import org.eclipse.jface.text.source.inlined.InlinedAnnotationSupport;
+import org.eclipse.jface.text.tests.util.DisplayHelper;
+
+public class CodeMiningLineHeaderAnnotationTest {
+
+	private SourceViewer fViewer;
+
+	private Shell fShell;
+
+	private Document document;
+
+	@Before
+	public void setUp() {
+		fShell= new Shell(Display.getDefault());
+		fShell.setSize(500, 200);
+		fShell.setLayout(new FillLayout());
+		fViewer= new SourceViewer(fShell, null, SWT.NONE);
+		final StyledText textWidget= fViewer.getTextWidget();
+		document= new Document("a");
+		textWidget.setText(document.get());
+		fViewer.setDocument(document, new AnnotationModel());
+		final Display display= textWidget.getDisplay();
+		fShell.open();
+		Assert.assertTrue(new DisplayHelper() {
+			@Override
+			protected boolean condition() {
+				return fViewer.getTextWidget().isVisible();
+			}
+		}.waitForCondition(display, 3000));
+		DisplayHelper.sleep(textWidget.getDisplay(), 1000);
+	}
+
+	@After
+	public void tearDown() {
+		fViewer= null;
+	}
+
+	@Test
+	public void testGetHeightDoesNotReturnZero() throws Exception {
+		var cut= new CodeMiningLineHeaderAnnotation(new Position(0, 0), fViewer);
+		var s= new InlinedAnnotationSupport();
+		s.install(fViewer, new AnnotationPainter(fViewer, null));
+		var m= AbstractInlinedAnnotation.class.getDeclaredMethod("setSupport", InlinedAnnotationSupport.class);
+		m.setAccessible(true);
+		m.invoke(cut, s);
+		cut.update(Arrays.asList(new LineHeaderCodeMining(0, document, null) {
+			@Override
+			public String getLabel() {
+				return "mining";
+			}
+		}), null);
+		// https: //github.com/eclipse-platform/eclipse.platform.ui/issues/2786
+		assertNotEquals(0, cut.getHeight()); // getHeight should not return 0, otherwise editor content starts jumping around
+	}
+}