Test added

tests/system/src/test/java/test/javafx/embed/swing/JFXPanelNPETest.java

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+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package test.javafx.embed.swing;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import javax.swing.JFrame;
+import javax.swing.SwingUtilities;
+
+import javafx.application.Application;
+import javafx.application.Platform;
+import javafx.embed.swing.JFXPanel;
+import javafx.scene.Scene;
+import javafx.scene.control.Button;
+import javafx.stage.Stage;
+
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Assert;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import test.util.Util;
+
+public class JFXPanelNPETest implements Thread.UncaughtExceptionHandler {
+    // Used to launch the application before running any test
+    private static final CountDownLatch launchLatch = new CountDownLatch(1);
+    private static CountDownLatch latch = new CountDownLatch(1);
+    private static Throwable th;
+
+    JFrame jframe;
+
+    // Application class. An instance is created and initialized before running
+    // the first test, and it lives through the execution of all tests.
+    public static class MyApp extends Application {
+        @Override
+        public void start(Stage primaryStage) throws Exception {
+            Platform.setImplicitExit(false);
+            Assert.assertTrue(Platform.isFxApplicationThread());
+            Assert.assertNotNull(primaryStage);
+
+            launchLatch.countDown();
+        }
+    }
+
+    @BeforeClass
+    public static void doSetupOnce() throws Exception {
+        Util.launch(launchLatch, MyApp.class);
+        Assert.assertEquals(0, launchLatch.getCount());
+    }
+
+    @AfterClass
+    public static void doTeardownOnce() {
+        Util.shutdown();
+    }
+
+    @After
+    public void doCleanup() {
+        if (jframe != null) {
+            SwingUtilities.invokeLater(() -> jframe.dispose());
+        }
+    }
+
+    @Test
+    public void testRemoveAddJFXPanel() throws Throwable {
+
+        JFrame frame = new JFrame("FX");
+        final JFXPanel fxPanel = new JFXPanel();
+        // fxPanel added to frame for the first time
+        frame.add(fxPanel);
+        frame.setSize(200, 200);
+        frame.setVisible(true);
+
+        Platform.runLater(() -> {
+            Scene scene = new Scene(new Button("Testbutton"));
+            fxPanel.setScene(scene);
+                Thread.currentThread().setUncaughtExceptionHandler(this);
+                SwingUtilities.invokeLater(() -> {
+		    // fxPanel removed from frame
+		    frame.remove(fxPanel);
+		    // fxPanel added to frame again
+		    frame.add(fxPanel); // <-- leads to NullPointerException
+            });
+        });
+        latch.await(5, TimeUnit.SECONDS);
+        System.out.println("throwable " + th);
+        if (th != null) {
+            throw th;
+        }
+    }
+
+    public void uncaughtException(Thread thread, Throwable throwable) {
+        th = throwable;
+        latch.countDown();
+    }
+}