Bug 547683 - Add non-UI Thread access to last known selection

Adds ITextViewerExtension9.getLastKnownSelection() method that gives
access to
last known value for the selection without requiring UI Thread.

The new Generic Editor test case shows how this can be leveraged in
ContentAssistProcessors.

Change-Id: I8a4831c08f7ff1ade07f2a12ad8d0d2c682a372c
Signed-off-by: Mickael Istria <mistria@redhat.com>

14 files changed, 320 insertions, 14 deletions

diff --git a/org.eclipse.jface.text.tests/META-INF/MANIFEST.MF b/org.eclipse.jface.text.tests/META-INF/MANIFEST.MF
index 1a42f604259..38d402f0196 100644
--- a/org.eclipse.jface.text.tests/META-INF/MANIFEST.MF
+++ b/org.eclipse.jface.text.tests/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %Plugin.name
 Bundle-SymbolicName: org.eclipse.jface.text.tests
-Bundle-Version: 3.11.800.qualifier
+Bundle-Version: 3.11.900.qualifier
 Bundle-Vendor: %Plugin.providerName
 Bundle-Localization: plugin
 Export-Package: 
@@ -16,7 +16,7 @@ Export-Package:
  org.eclipse.jface.text.tests.templates.persistence,
  org.eclipse.jface.text.tests.util
 Require-Bundle: 
- org.eclipse.jface.text;bundle-version="[3.5.0,4.0.0)",
+ org.eclipse.jface.text;bundle-version="[3.16.0,4.0.0)",
  org.eclipse.jface;bundle-version="[3.5.0,4.0.0)",
  org.junit;bundle-version="4.12.0",
  org.eclipse.text.tests;bundle-version="[3.5.0,4.0.0)",
diff --git a/org.eclipse.jface.text.tests/pom.xml b/org.eclipse.jface.text.tests/pom.xml
index 805ed7bf71d..3b95c973012 100644
--- a/org.eclipse.jface.text.tests/pom.xml
+++ b/org.eclipse.jface.text.tests/pom.xml
@@ -19,7 +19,7 @@
   </parent>
   <groupId>org.eclipse.jface</groupId>
   <artifactId>org.eclipse.jface.text.tests</artifactId>
-  <version>3.11.800-SNAPSHOT</version>
+  <version>3.11.900-SNAPSHOT</version>
   <packaging>eclipse-test-plugin</packaging>
   <properties>
   	<testSuite>${project.artifactId}</testSuite>
diff --git a/org.eclipse.jface.text.tests/src/org/eclipse/jface/text/tests/TextViewerTest.java b/org.eclipse.jface.text.tests/src/org/eclipse/jface/text/tests/TextViewerTest.java
index 2b2dd2e685e..a53a00dfc2e 100644
--- a/org.eclipse.jface.text.tests/src/org/eclipse/jface/text/tests/TextViewerTest.java
+++ b/org.eclipse.jface.text.tests/src/org/eclipse/jface/text/tests/TextViewerTest.java
@@ -11,7 +11,7 @@
  * Contributors:
  * 	   Sergey Prigogin (Google) - initial API and implementation
  * 	   Mickael Istria (Red Hat Inc.) - [Bug 544708] Ctrl+Home
- * 	   Paul Pazderski - [Bug 545530] Test for TextViewer's default IDocumentAdapter implementation. 
+ * 	   Paul Pazderski - [Bug 545530] Test for TextViewer's default IDocumentAdapter implementation.
  *******************************************************************************/
 package org.eclipse.jface.text.tests;
 
@@ -27,6 +27,7 @@ import org.junit.Rule;
 import org.junit.Test;
 
 import org.eclipse.swt.SWT;
+import org.eclipse.swt.custom.StyledText;
 import org.eclipse.swt.custom.StyledTextContent;
 import org.eclipse.swt.layout.FillLayout;
 import org.eclipse.swt.widgets.Control;
@@ -35,10 +36,16 @@ import org.eclipse.swt.widgets.Event;
 import org.eclipse.swt.widgets.Listener;
 import org.eclipse.swt.widgets.Shell;
 
+import org.eclipse.core.runtime.IStatus;
+import org.eclipse.core.runtime.Status;
+import org.eclipse.core.runtime.jobs.Job;
+
 import org.eclipse.jface.util.Util;
 
+import org.eclipse.jface.text.BlockTextSelection;
 import org.eclipse.jface.text.Document;
 import org.eclipse.jface.text.IDocumentAdapter;
+import org.eclipse.jface.text.ITextSelection;
 import org.eclipse.jface.text.ITextViewer;
 import org.eclipse.jface.text.TextViewer;
 import org.eclipse.jface.text.source.SourceViewer;
@@ -76,6 +83,96 @@ public class TextViewerTest {
 	}
 
 	@Test
+	public void testCaretMoveChangesSelection() throws Exception {
+		Shell shell= new Shell();
+		try {
+			TextViewer textViewer= new TextViewer(shell, SWT.NONE);
+			Document document= new Document("abc");
+			textViewer.setDocument(document);
+			int len= document.getLength();
+			// Select the whole document with the caret at the beginning.
+			textViewer.setSelectedRange(0, len);
+			ITextSelection selection = (ITextSelection)textViewer.getSelectionProvider().getSelection();
+			assertEquals(0, selection.getOffset());
+			assertEquals(len, selection.getLength());
+			textViewer.getTextWidget().setCaretOffset(1);
+			selection = (ITextSelection)textViewer.getSelectionProvider().getSelection();
+			assertEquals(1, selection.getOffset());
+			assertEquals(0, selection.getLength());
+		} finally {
+			shell.dispose();
+		}
+	}
+
+	@Test
+	public void testGetCachedSelection() throws Exception {
+		Shell shell= new Shell();
+		try {
+			TextViewer textViewer= new TextViewer(shell, SWT.NONE);
+			Document document= new Document("abc");
+			textViewer.setDocument(document);
+			int len= document.getLength();
+			// Select the whole document with the caret at the beginning.
+			textViewer.setSelectedRange(0, len);
+			checkInAndOutUIThread(() -> {
+				ITextSelection selection = textViewer.getLastKnownSelection();
+				assertEquals(0, selection.getOffset());
+				assertEquals(len, selection.getLength());
+			});
+		} finally {
+			shell.dispose();
+		}
+	}
+
+	@Test
+	public void testBlockSelectionAccessors() throws Exception {
+		Shell shell= new Shell();
+		try {
+			ITextViewer textViewer= new TextViewer(shell, SWT.NONE);
+			Document document= new Document("0123\n4567\n89ab\ncdef");
+			textViewer.setDocument(document);
+			// Select the whole document with the caret at the beginning.
+			StyledText textWidget= textViewer.getTextWidget();
+			textWidget.setBlockSelection(true);
+			shell.setLayout(new FillLayout());
+			shell.open();
+			textViewer.getSelectionProvider().setSelection(new BlockTextSelection(textViewer.getDocument(), 1, 1, 2, 2, textWidget.getTabs()));
+			BlockTextSelection sel = (BlockTextSelection)textViewer.getSelectionProvider().getSelection();
+			assertEquals(1, sel.getStartLine());
+			assertEquals(2, sel.getEndLine());
+			assertEquals(1, sel.getStartColumn());
+			assertEquals(2, sel.getEndColumn());
+		} finally {
+			shell.dispose();
+		}
+	}
+
+
+	private void checkInAndOutUIThread(Runnable r) throws InterruptedException {
+		// first run in UI Thread, forward exceptions
+		r.run();
+		// then run in non-UI Thread
+		Job job = Job.create("Check in non-UI Thread", monitor -> {
+			try {
+				r.run();
+				return Status.OK_STATUS;
+			} catch (Throwable t) {
+				return new Status(IStatus.ERROR, "org.eclipse.jface.text.tests", t.getMessage(), t);
+			}
+		});
+		job.schedule();
+		job.join();
+		if (!job.getResult().isOK()) {
+			Throwable ex = job.getResult().getException();
+			if (ex != null) {
+				throw new AssertionError("Assertion fail in non-UI Thread", ex);
+			} else {
+				fail(job.getResult().toString());
+			}
+		}
+	}
+
+	@Test
 	public void testCtrlHomeViewportListener() {
 		Assume.assumeFalse("See bug 541415. For whatever reason, this shortcut doesn't work on Mac", Util.isMac());
 		Shell shell= new Shell();
diff --git a/org.eclipse.jface.text/.settings/.api_filters b/org.eclipse.jface.text/.settings/.api_filters
index 1396277426a..9a61dee5da1 100644
--- a/org.eclipse.jface.text/.settings/.api_filters
+++ b/org.eclipse.jface.text/.settings/.api_filters
@@ -1,5 +1,29 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <component id="org.eclipse.jface.text" version="2">
+    <resource path="src/META-INF/MANIFEST.MF">
+        <filter comment="Workaround https://bugs.eclipse.org/bugs/show_bug.cgi?id=548680#c11" id="926941240">
+            <message_arguments>
+                <message_argument value="3.16.0"/>
+                <message_argument value="3.15.200"/>
+            </message_arguments>
+        </filter>
+    </resource>
+    <resource path="src/META-INF/MANIFEST.MF">
+        <filter comment="Workaround https://bugs.eclipse.org/bugs/show_bug.cgi?id=548680#c11" id="923795461">
+            <message_arguments>
+                <message_argument value="3.16.0"/>
+                <message_argument value="3.15.200"/>
+            </message_arguments>
+        </filter>
+    </resource>
+    <resource path="src/org/eclipse/jface/text/ITextViewer.java" type="org.eclipse.jface.text.ITextViewer">
+        <filter comment="Method introduction unlikely to collide with existing implementations." id="404000815">
+            <message_arguments>
+                <message_argument value="org.eclipse.jface.text.ITextViewer"/>
+                <message_argument value="getLastKnownSelection()"/>
+            </message_arguments>
+        </filter>
+    </resource>
     <resource path="src/org/eclipse/jface/text/TextViewer.java" type="org.eclipse.jface.text.TextViewer">
         <filter id="572522506">
             <message_arguments>
diff --git a/org.eclipse.jface.text/META-INF/MANIFEST.MF b/org.eclipse.jface.text/META-INF/MANIFEST.MF
index 861f47e4ad5..38c33e54307 100644
--- a/org.eclipse.jface.text/META-INF/MANIFEST.MF
+++ b/org.eclipse.jface.text/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.jface.text
-Bundle-Version: 3.15.400.qualifier
+Bundle-Version: 3.16.0.qualifier
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin
 Export-Package: 
diff --git a/org.eclipse.jface.text/pom.xml b/org.eclipse.jface.text/pom.xml
index ddbe958b909..3c59bdaaac5 100644
--- a/org.eclipse.jface.text/pom.xml
+++ b/org.eclipse.jface.text/pom.xml
@@ -18,6 +18,6 @@
   </parent>
   <groupId>org.eclipse.jface</groupId>
   <artifactId>org.eclipse.jface.text</artifactId>
-  <version>3.15.400-SNAPSHOT</version>
+  <version>3.16.0-SNAPSHOT</version>
   <packaging>eclipse-plugin</packaging>
 </project>
diff --git a/org.eclipse.jface.text/src/org/eclipse/jface/text/BlockTextSelection.java b/org.eclipse.jface.text/src/org/eclipse/jface/text/BlockTextSelection.java
index 473695266c2..d75a296aaed 100644
--- a/org.eclipse.jface.text/src/org/eclipse/jface/text/BlockTextSelection.java
+++ b/org.eclipse.jface.text/src/org/eclipse/jface/text/BlockTextSelection.java
@@ -159,4 +159,29 @@ public class BlockTextSelection extends TextSelection implements IBlockTextSelec
 		}
 		return new IRegion[] {new Region(getOffset(), getLength())};
 	}
+
+	/**
+	 * @since 3.16
+	 */
+	@Override
+	public String toString() {
+		StringBuilder sb= new StringBuilder();
+		sb.append("BlockTextSelection [offset: ").append(getOffset()); //$NON-NLS-1$
+		sb.append(", startLine: ").append(fStartLine); //$NON-NLS-1$
+		if (fEndLine != fStartLine) {
+			sb.append(", endLine: ").append(fEndLine); //$NON-NLS-1$
+		}
+		sb.append(", startColumn: ").append(fStartColumn); //$NON-NLS-1$
+		if (fEndColumn != fStartColumn) {
+			sb.append(", endColumn").append(fEndColumn); //$NON-NLS-1$
+		}
+		if (getLength() != 0) {
+			sb.append(", text: ").append(getText()); //$NON-NLS-1$
+		}
+		if (getDocument() != null) {
+			sb.append(", document: ").append(getDocument()); //$NON-NLS-1$
+		}
+		sb.append("]"); //$NON-NLS-1$
+		return sb.toString();
+	}
 }
diff --git a/org.eclipse.jface.text/src/org/eclipse/jface/text/ITextViewerExtension9.java b/org.eclipse.jface.text/src/org/eclipse/jface/text/ITextViewerExtension9.java
new file mode 100644
index 00000000000..c26d7e82060
--- /dev/null
+++ b/org.eclipse.jface.text/src/org/eclipse/jface/text/ITextViewerExtension9.java
@@ -0,0 +1,38 @@
+/*******************************************************************************
+ * Copyright (c) 2019 Red Hat Inc. 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
+ *******************************************************************************/
+package org.eclipse.jface.text;
+
+import org.eclipse.jface.viewers.ISelectionProvider;
+
+/**
+ * Extension interface for {@link org.eclipse.jface.text.ITextViewer}. Adds the ability to retrieve
+ * the last known selection from outside of the UI Thread.
+ *
+ * @since 3.16
+ */
+public interface ITextViewerExtension9 {
+
+
+	/**
+	 * Returns the last known selection from a cache, without polling widget.
+	 * <p>
+	 * This may <strong>not</strong> be the current selection. Indeed, operations that change the
+	 * selection without sending related events may not refresh the returned value.
+	 * </p>
+	 * <p>
+	 * As opposed to {@link ISelectionProvider#getSelection()} that usually requires UI Thread, this
+	 * method can run from any thread.
+	 * </p>
+	 *
+	 * @return the last known selection.
+	 */
+	public ITextSelection getLastKnownSelection();
+}
diff --git a/org.eclipse.jface.text/src/org/eclipse/jface/text/TextViewer.java b/org.eclipse.jface.text/src/org/eclipse/jface/text/TextViewer.java
index 27ae2c3b094..9a274e3d94b 100644
--- a/org.eclipse.jface.text/src/org/eclipse/jface/text/TextViewer.java
+++ b/org.eclipse.jface.text/src/org/eclipse/jface/text/TextViewer.java
@@ -113,7 +113,7 @@ import org.eclipse.jface.text.projection.ChildDocumentManager;
  * @noextend This class is not intended to be subclassed by clients.
  */
 public class TextViewer extends Viewer implements
-					ITextViewer, ITextViewerExtension, ITextViewerExtension2, ITextViewerExtension4, ITextViewerExtension6, ITextViewerExtension7, ITextViewerExtension8,
+		ITextViewer, ITextViewerExtension, ITextViewerExtension2, ITextViewerExtension4, ITextViewerExtension6, ITextViewerExtension7, ITextViewerExtension8, ITextViewerExtension9,
 					IEditingSupportRegistry, ITextOperationTarget, ITextOperationTargetExtension,
 					IWidgetTokenOwner, IWidgetTokenOwnerExtension, IPostSelectionProvider {
 
@@ -1752,6 +1752,12 @@ public class TextViewer extends Viewer implements
 				selectionChanged(event.x, event.y - event.x);
 			}
 		});
+		fTextWidget.addCaretListener(e -> {
+			// caret listener is invoked before widget actually performs the caret (and selection)
+			// change. So we can't update the selection synchronously on event, instead, we
+			// delay the selection update.
+			fTextWidget.getDisplay().asyncExec(() -> selectionChanged(e.caretOffset, 0));
+		});
 
 		fCursorListener= new CursorListener();
 		fCursorListener.install();
@@ -2234,6 +2240,21 @@ public class TextViewer extends Viewer implements
 
 	//---- Selection
 
+	/**
+	 * Caches the selection value. Is only modified from inside UI Thread. Can be accessed from any
+	 * thread.
+	 */
+	private volatile ITextSelection cachedSelection= TextSelection.emptySelection();
+
+	private void updateSelectionCache() {
+		cachedSelection= computeSelection();
+	}
+
+	@Override
+	public ITextSelection getLastKnownSelection() {
+		return cachedSelection;
+	}
+
 	@Override
 	public Point getSelectedRange() {
 
@@ -2272,6 +2293,7 @@ public class TextViewer extends Viewer implements
 				selectionChanged(selectionRange[0], selectionRange[1]);
 			}
 		}
+		updateSelectionCache();
 	}
 
 	/**
@@ -2410,6 +2432,12 @@ public class TextViewer extends Viewer implements
 
 	@Override
 	public ISelection getSelection() {
+		final ITextSelection res= computeSelection();
+		cachedSelection= res;
+		return res;
+	}
+
+	private ITextSelection computeSelection() {
 		if (fTextWidget != null && fTextWidget.getBlockSelection()) {
 			int[] ranges= fTextWidget.getSelectionRanges();
 			int startOffset= ranges[0];
@@ -2574,6 +2602,7 @@ public class TextViewer extends Viewer implements
 	 * @param length the length of the newly selected range in the visible document
 	 */
 	protected void selectionChanged(int offset, int length) {
+		updateSelectionCache();
 		queuePostSelectionChanged(true);
 		fireSelectionChanged(offset, length);
 	}
diff --git a/org.eclipse.ui.genericeditor.tests/META-INF/MANIFEST.MF b/org.eclipse.ui.genericeditor.tests/META-INF/MANIFEST.MF
index a9071960add..a2dcaad225e 100644
--- a/org.eclipse.ui.genericeditor.tests/META-INF/MANIFEST.MF
+++ b/org.eclipse.ui.genericeditor.tests/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %Plugin.name
 Bundle-SymbolicName: org.eclipse.ui.genericeditor.tests;singleton:=true
-Bundle-Version: 1.1.400.qualifier
+Bundle-Version: 1.1.500.qualifier
 Bundle-Vendor: %Plugin.providerName
 Bundle-Localization: plugin
 Export-Package: org.eclipse.ui.genericeditor.tests,
@@ -13,7 +13,7 @@ Require-Bundle: org.eclipse.core.runtime;bundle-version="[3.6.0,4.0.0)",
  org.eclipse.text;bundle-version="[3.5.0,4.0.0)",
  org.eclipse.ui.genericeditor,
  org.eclipse.core.resources;bundle-version="3.11.0",
- org.eclipse.jface.text;bundle-version="3.11.0",
+ org.eclipse.jface.text;bundle-version="3.16.0",
  org.eclipse.ui;bundle-version="3.108.0",
  org.eclipse.ui.workbench.texteditor;bundle-version="3.10.0",
  org.eclipse.ui.ide;bundle-version="3.11.0",
diff --git a/org.eclipse.ui.genericeditor.tests/plugin.xml b/org.eclipse.ui.genericeditor.tests/plugin.xml
index c2a259aa126..2bf886673d6 100644
--- a/org.eclipse.ui.genericeditor.tests/plugin.xml
+++ b/org.eclipse.ui.genericeditor.tests/plugin.xml
@@ -35,6 +35,10 @@
 	        </test>
 	      </enabledWhen>
 		</contentAssistProcessor>
+	<contentAssistProcessor
+		class="org.eclipse.ui.genericeditor.tests.contributions.ToUpperCaseContentAssistProcessor"
+		contentType="org.eclipse.ui.genericeditor.tests.content-type">
+	</contentAssistProcessor>
 	</extension>
 	<extension
 			point="org.eclipse.ui.genericeditor.hoverProviders">
diff --git a/org.eclipse.ui.genericeditor.tests/pom.xml b/org.eclipse.ui.genericeditor.tests/pom.xml
index 030439183b3..a417d6d93d2 100644
--- a/org.eclipse.ui.genericeditor.tests/pom.xml
+++ b/org.eclipse.ui.genericeditor.tests/pom.xml
@@ -19,7 +19,7 @@
   </parent>
   <groupId>org.eclipse.ui</groupId>
   <artifactId>org.eclipse.ui.genericeditor.tests</artifactId>
-  <version>1.1.400-SNAPSHOT</version>
+  <version>1.1.500-SNAPSHOT</version>
   <packaging>eclipse-test-plugin</packaging>
   <properties>
   	<testSuite>${project.artifactId}</testSuite>
diff --git a/org.eclipse.ui.genericeditor.tests/src/org/eclipse/ui/genericeditor/tests/CompletionTest.java b/org.eclipse.ui.genericeditor.tests/src/org/eclipse/ui/genericeditor/tests/CompletionTest.java
index e296de61134..d6504cd6289 100644
--- a/org.eclipse.ui.genericeditor.tests/src/org/eclipse/ui/genericeditor/tests/CompletionTest.java
+++ b/org.eclipse.ui.genericeditor.tests/src/org/eclipse/ui/genericeditor/tests/CompletionTest.java
@@ -56,6 +56,7 @@ public class CompletionTest extends AbstratGenericEditorTest {
 	@Test
 	public void testCompletion() throws Exception {
 		final Set<Shell> beforeShells = Arrays.stream(editor.getSite().getShell().getDisplay().getShells()).filter(Shell::isVisible).collect(Collectors.toSet());
+		editor.selectAndReveal(3, 0);
 		openConentAssist();
 		this.completionShell= findNewShell(beforeShells);
 		final Table completionProposalList = findCompletionSelectionControl(completionShell);
@@ -65,11 +66,28 @@ public class CompletionTest extends AbstratGenericEditorTest {
 	}
 
 	@Test
+	public void testCompletionUsingViewerSelection() throws Exception {
+		final Set<Shell> beforeShells = Arrays.stream(editor.getSite().getShell().getDisplay().getShells()).filter(Shell::isVisible).collect(Collectors.toSet());
+		editor.getDocumentProvider().getDocument(editor.getEditorInput()).set("abc");
+		editor.selectAndReveal(0, 3);
+		openConentAssist();
+		this.completionShell= findNewShell(beforeShells);
+		final Table completionProposalList = findCompletionSelectionControl(completionShell);
+		assertTrue(new DisplayHelper() {
+			@Override
+			protected boolean condition() {
+				return Arrays.stream(completionProposalList.getItems()).map(TableItem::getText).anyMatch("ABC"::equals);
+			}
+		}.waitForCondition(completionProposalList.getDisplay(), 200));
+	}
+
+	@Test
 	public void testEnabledWhenCompletion() throws Exception {
 		// Confirm that when disabled, a completion shell is present
 		EnabledPropertyTester.setEnabled(false);
 		createAndOpenFile("enabledWhen.txt", "bar 'bar'");
 		final Set<Shell> beforeShells = Arrays.stream(editor.getSite().getShell().getDisplay().getShells()).filter(Shell::isVisible).collect(Collectors.toSet());
+		editor.selectAndReveal(3, 0);
 		openConentAssist();
 		Shell[] afterShells = Arrays.stream(editor.getSite().getShell().getDisplay().getShells())
 				.filter(Shell::isVisible)
@@ -82,12 +100,12 @@ public class CompletionTest extends AbstratGenericEditorTest {
 		EnabledPropertyTester.setEnabled(true);
 		createAndOpenFile("enabledWhen.txt", "bar 'bar'");
 		final Set<Shell> beforeEnabledShells = Arrays.stream(editor.getSite().getShell().getDisplay().getShells()).filter(Shell::isVisible).collect(Collectors.toSet());
+		editor.selectAndReveal(3, 0);
 		openConentAssist();
 		assertNotNull(findNewShell(beforeEnabledShells));
 	}
 
 	private void openConentAssist() {
-		editor.selectAndReveal(3, 0);
 		ContentAssistAction action = (ContentAssistAction) editor.getAction(ITextEditorActionConstants.CONTENT_ASSIST);
 		action.update();
 		action.run();
@@ -103,13 +121,12 @@ public class CompletionTest extends AbstratGenericEditorTest {
 	 */
 	private void checkCompletionContent(final Table completionProposalList) {
 		// should be instantaneous, but happens to go asynchronous on CI so let's allow a wait
-		new DisplayHelper() {
+		assertTrue(new DisplayHelper() {
 			@Override
 			protected boolean condition() {
 				return completionProposalList.getItemCount() == 2;
 			}
-		}.waitForCondition(completionProposalList.getDisplay(), 200);
-		assertEquals(2, completionProposalList.getItemCount());
+		}.waitForCondition(completionProposalList.getDisplay(), 200));
 		final TableItem computingItem = completionProposalList.getItem(0);
 		assertTrue("Missing computing info entry", computingItem.getText().contains("Computing")); //$NON-NLS-1$ //$NON-NLS-2$
 		TableItem completionProposalItem = completionProposalList.getItem(1);
@@ -142,6 +159,7 @@ public class CompletionTest extends AbstratGenericEditorTest {
 	@Test
 	public void testCompletionFreeze_bug521484() throws Exception {
 		final Set<Shell> beforeShells = Arrays.stream(editor.getSite().getShell().getDisplay().getShells()).filter(Shell::isVisible).collect(Collectors.toSet());
+		editor.selectAndReveal(3, 0);
 		openConentAssist();
 		this.completionShell= findNewShell(beforeShells);
 		final Table completionProposalList = findCompletionSelectionControl(this.completionShell);
diff --git a/org.eclipse.ui.genericeditor.tests/src/org/eclipse/ui/genericeditor/tests/contributions/ToUpperCaseContentAssistProcessor.java b/org.eclipse.ui.genericeditor.tests/src/org/eclipse/ui/genericeditor/tests/contributions/ToUpperCaseContentAssistProcessor.java
new file mode 100644
index 00000000000..9c2b8e56a80
--- /dev/null
+++ b/org.eclipse.ui.genericeditor.tests/src/org/eclipse/ui/genericeditor/tests/contributions/ToUpperCaseContentAssistProcessor.java
@@ -0,0 +1,71 @@
+/*******************************************************************************
+ * Copyright (c) 2019 Red Hat Inc. 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
+ *******************************************************************************/
+package org.eclipse.ui.genericeditor.tests.contributions;
+
+import org.eclipse.jface.text.BadLocationException;
+import org.eclipse.jface.text.ITextSelection;
+import org.eclipse.jface.text.ITextViewer;
+import org.eclipse.jface.text.ITextViewerExtension9;
+import org.eclipse.jface.text.contentassist.CompletionProposal;
+import org.eclipse.jface.text.contentassist.ICompletionProposal;
+import org.eclipse.jface.text.contentassist.IContentAssistProcessor;
+import org.eclipse.jface.text.contentassist.IContextInformation;
+import org.eclipse.jface.text.contentassist.IContextInformationValidator;
+
+public class ToUpperCaseContentAssistProcessor implements IContentAssistProcessor {
+
+	@Override
+	public ICompletionProposal[] computeCompletionProposals(ITextViewer viewer, int offset) {
+		if (!(viewer instanceof ITextViewerExtension9)) {
+			return new ICompletionProposal[0];
+		}
+		ITextSelection selection= ((ITextViewerExtension9)viewer).getLastKnownSelection();
+		if (selection.isEmpty() || selection.getLength() == 0) {
+			return new ICompletionProposal[0];
+		}
+		String initialText;
+		try {
+			initialText= viewer.getDocument().get(selection.getOffset(), selection.getLength());
+			return new ICompletionProposal[] {
+				new CompletionProposal(initialText.toUpperCase(), selection.getOffset(), initialText.length(), selection.getOffset() + initialText.length())
+			};
+		} catch (BadLocationException e) {
+			return new ICompletionProposal[0];
+		}
+
+	}
+
+	@Override
+	public IContextInformation[] computeContextInformation(ITextViewer viewer, int offset) {
+		return new IContextInformation[0];
+	}
+
+	@Override
+	public char[] getCompletionProposalAutoActivationCharacters() {
+		return new char[0];
+	}
+
+	@Override
+	public char[] getContextInformationAutoActivationCharacters() {
+		return new char[0];
+	}
+
+	@Override
+	public String getErrorMessage() {
+		return getClass().getName();
+	}
+
+	@Override
+	public IContextInformationValidator getContextInformationValidator() {
+		return null;
+	}
+
+}