Bug 271336 Test failures on Mac OS
diff --git a/org.eclipse.jdt.debug.tests/tests/org/eclipse/jdt/debug/tests/core/StringSubstitutionTests.java b/org.eclipse.jdt.debug.tests/tests/org/eclipse/jdt/debug/tests/core/StringSubstitutionTests.java
index 22f361c..62f0f78 100644
--- a/org.eclipse.jdt.debug.tests/tests/org/eclipse/jdt/debug/tests/core/StringSubstitutionTests.java
+++ b/org.eclipse.jdt.debug.tests/tests/org/eclipse/jdt/debug/tests/core/StringSubstitutionTests.java
@@ -766,6 +766,7 @@
 		Runnable r = new Runnable() {
 			public void run() {
 				IWorkbenchPage page = DebugUIPlugin.getActiveWorkbenchWindow().getActivePage();
+				assertNotNull("the active workbench window page should not be null", page);
 				IViewPart part;
 				try {
 					part = page.showView("org.eclipse.ui.views.ResourceNavigator");
diff --git a/org.eclipse.jdt.debug.tests/tests/org/eclipse/jdt/debug/tests/launching/RefreshTabTests.java b/org.eclipse.jdt.debug.tests/tests/org/eclipse/jdt/debug/tests/launching/RefreshTabTests.java
index d433a18..e42b567 100755
--- a/org.eclipse.jdt.debug.tests/tests/org/eclipse/jdt/debug/tests/launching/RefreshTabTests.java
+++ b/org.eclipse.jdt.debug.tests/tests/org/eclipse/jdt/debug/tests/launching/RefreshTabTests.java
@@ -45,6 +45,7 @@
 		Runnable r = new Runnable() {
 			public void run() {
 				IWorkbenchPage page = DebugUIPlugin.getActiveWorkbenchWindow().getActivePage();
+				assertNotNull("The acive workbench page should not be null", page);
 				IViewPart part;
 				try {
 					part = page.showView("org.eclipse.ui.views.ResourceNavigator"); //$NON-NLS-1$