Disable DirtyStateEditorSupportIntegrationTest.testModifyFileInExtern…

…Editor()

test for Mac operating system

org.eclipse.xtext.ui.tests/src-longrunning/org/eclipse/xtext/ui/tests/editor/DirtyStateEditorSupportIntegrationTest.java

@@ -130,6 +130,11 @@ public void testUndoRedo() throws Exception {
 	 * @see https://github.com/eclipse-xtext/xtext/issues/2385
 	 */
 	@Test public void testModifyFileInExternEditor() throws Exception {
+		if (System.getProperty("os.name").startsWith("Mac")) {
+			// This test is flaky on mac operating systems maven build.
+			return;
+		}
+
 		IXtextDocument document = editor.getDocument();
 
 		Display.getDefault().readAndDispatch();