Bug 419228 - [Net] PreferenceModifyListener pollutes exported preferences

Change-Id: I2907c8cd1e9cd9a0a662c45652a69948e8cc75da
Signed-off-by: Szymon Ptaszkiewicz <szymon.ptaszkiewicz@pl.ibm.com>

3 files changed, 80 insertions, 6 deletions

diff --git a/bundles/org.eclipse.core.net/src/org/eclipse/core/internal/net/PreferenceModifyListener.java b/bundles/org.eclipse.core.net/src/org/eclipse/core/internal/net/PreferenceModifyListener.java
index 0f5198221..57f9d3b4a 100644
--- a/bundles/org.eclipse.core.net/src/org/eclipse/core/internal/net/PreferenceModifyListener.java
+++ b/bundles/org.eclipse.core.net/src/org/eclipse/core/internal/net/PreferenceModifyListener.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2007, 2010 IBM Corporation and others.
+ * Copyright (c) 2007, 2013 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -14,6 +14,7 @@ import org.eclipse.core.runtime.preferences.ConfigurationScope;
 import org.eclipse.core.runtime.preferences.IEclipsePreferences;
 import org.eclipse.core.runtime.preferences.InstanceScope;
 import org.osgi.service.prefs.BackingStoreException;
+import org.osgi.service.prefs.Preferences;
 
 public class PreferenceModifyListener extends
 		org.eclipse.core.runtime.preferences.PreferenceModifyListener {
@@ -23,11 +24,20 @@ public class PreferenceModifyListener extends
 	}
 	
 	public IEclipsePreferences preApply(IEclipsePreferences node) {
+		// the node does not need to be the root of the hierarchy
+		Preferences root = node.node("/"); //$NON-NLS-1$
 		try {
-			if (node.nodeExists(InstanceScope.SCOPE)) {
-				((ProxyManager)ProxyManager.getProxyManager()).migrateInstanceScopePreferences(
-								node.node(InstanceScope.SCOPE).node(Activator.ID), 
-								node.node(ConfigurationScope.SCOPE).node(Activator.ID), false);
+			// we must not create empty preference nodes, so first check if the node exists
+			if (root.nodeExists(InstanceScope.SCOPE)) {
+				Preferences instance = root.node(InstanceScope.SCOPE);
+				// we must not create empty preference nodes, so first check if the node exists
+				if (instance.nodeExists(Activator.ID)) {
+					((ProxyManager) ProxyManager.getProxyManager())
+							.migrateInstanceScopePreferences(
+									instance.node(Activator.ID),
+									root.node(ConfigurationScope.SCOPE).node(
+											Activator.ID), false);
+				}
 			}
 		} catch (BackingStoreException e) {
 			Activator.logError("Could not access instance preferences", e); //$NON-NLS-1$
diff --git a/tests/org.eclipse.core.tests.net/src/org/eclipse/core/tests/net/AllNetTests.java b/tests/org.eclipse.core.tests.net/src/org/eclipse/core/tests/net/AllNetTests.java
index 3d2441984..d95358ade 100644
--- a/tests/org.eclipse.core.tests.net/src/org/eclipse/core/tests/net/AllNetTests.java
+++ b/tests/org.eclipse.core.tests.net/src/org/eclipse/core/tests/net/AllNetTests.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2007 IBM Corporation and others.
+ * Copyright (c) 2007, 2013 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -25,6 +25,7 @@ public class AllNetTests extends TestCase {
 	public static Test suite() {
 		TestSuite suite = new TestSuite();
 		suite.addTest(NetTest.suite());
+		suite.addTest(PreferenceModifyListenerTest.suite());
 		return suite;
 	}
 }
diff --git a/tests/org.eclipse.core.tests.net/src/org/eclipse/core/tests/net/PreferenceModifyListenerTest.java b/tests/org.eclipse.core.tests.net/src/org/eclipse/core/tests/net/PreferenceModifyListenerTest.java
new file mode 100644
index 000000000..96fc9eb24
--- /dev/null
+++ b/tests/org.eclipse.core.tests.net/src/org/eclipse/core/tests/net/PreferenceModifyListenerTest.java
@@ -0,0 +1,63 @@
+/*******************************************************************************
+ * Copyright (c) 2013 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.core.tests.net;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+
+import junit.framework.Test;
+import junit.framework.TestCase;
+
+import org.eclipse.core.internal.preferences.EclipsePreferences;
+import org.eclipse.core.runtime.CoreException;
+import org.eclipse.core.runtime.Platform;
+import org.eclipse.core.runtime.preferences.IEclipsePreferences;
+import org.eclipse.core.runtime.preferences.IExportedPreferences;
+import org.eclipse.core.runtime.preferences.IPreferencesService;
+import org.eclipse.core.runtime.preferences.InstanceScope;
+import org.osgi.service.prefs.BackingStoreException;
+
+public class PreferenceModifyListenerTest extends TestCase {
+	private static final String NODE_NAME = "bug419228";
+	private static final String KEY = "someKey";
+	private static final String VALUE = "someValue";
+
+	public static Test suite() {
+		return new PreferenceModifyListenerTest("testPreApply");
+	}
+
+	public PreferenceModifyListenerTest(String name) {
+		super(name);
+	}
+
+	public void testPreApply() throws BackingStoreException, CoreException {
+		// create a dummy node and export it to a stream
+		IEclipsePreferences toExport = InstanceScope.INSTANCE.getNode(NODE_NAME);
+		toExport.put(KEY, VALUE);
+		IPreferencesService service = Platform.getPreferencesService();
+		ByteArrayOutputStream stream = new ByteArrayOutputStream();
+		assertTrue(service.exportPreferences(toExport, stream, null).isOK());
+
+		// read preferences from a stream
+		IExportedPreferences exported = service.readPreferences(new ByteArrayInputStream(stream.toByteArray()));
+		exported = (IExportedPreferences) exported.node(InstanceScope.SCOPE).node(NODE_NAME);
+
+		// apply exported preferences to the global preferences hierarchy
+		assertTrue(service.applyPreferences(exported).isOK());
+
+		// verify that the node is not modified
+		String debugString = ((EclipsePreferences) exported.node("/")).toDeepDebugString();
+		assertFalse(debugString, exported.nodeExists("instance/org.eclipse.core.net"));
+		assertFalse(debugString, exported.nodeExists("/instance/org.eclipse.core.net"));
+		assertFalse(debugString, exported.nodeExists("configuration/org.eclipse.core.net"));
+		assertFalse(debugString, exported.nodeExists("/configuration/org.eclipse.core.net"));
+	}
+}