--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/runtime/cds/appcds/jigsaw/overridetests/src/test/jdk/test/Main.java	Mon Jul 29 10:34:20 2019 -0400
@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2015, 2019, 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.
+ *
+ * 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.
+ *
+ */
+
+/**
+ * Used with -p or --upgrade-module-path to exercise the replacement
+ * of classes in modules that are linked into the runtime image.
+ */
+
+package jdk.test;
+
+public class Main {
+    static final ClassLoader PLATFORM_LOADER = ClassLoader.getPlatformClassLoader();
+    static final ClassLoader SYS_LOADER      = ClassLoader.getSystemClassLoader();
+
+    public static void main(String[] args) throws Exception {
+        ClassLoader loader = null;
+        boolean shouldOverride = false;
+
+        /*
+         * 3 Arguments are passed to this test:
+         *   1. className: Name of the class to load.
+         *   2. loaderName: Either "platform" or "app", which specifies which ClassLoader is expected
+         *      to be the defining ClassLoader once the class is loaded. The initiating
+         *      ClassLoader is always the default ClassLoader (which should be the
+         *      app (system) ClassLoader.
+         *   3. shouldOverride: Either "true" or "false" to indicate whether the loaded class
+         *      should be the one we are attempting to override with (not the archived version).
+         */
+
+        assertTrue(args.length == 3, "Unexpected number of arguments: expected 3, actual " + args.length);
+        String className = args[0].replace('/', '.');
+        String loaderName = args[1]; // "platform" or "app"
+        String shouldOverrideName = args[2];  // "true" or "false"
+
+        if (loaderName.equals("app")) {
+            loader = SYS_LOADER;
+        } else if (loaderName.equals("platform")) {
+            loader = PLATFORM_LOADER;
+        } else {
+            assertTrue(false);
+        }
+
+        if (shouldOverrideName.equals("true")) {
+            shouldOverride = true;
+        } else if (shouldOverrideName.equals("false")) {
+            shouldOverride = false;
+        } else {
+            assertTrue(false);
+        }
+
+        // Load the class with the default ClassLoader.
+        Class<?> clazz = Class.forName(className, true, loader);
+        // Make sure we got the expected defining ClassLoader
+        testLoader(clazz, loader);
+
+        String s = null;
+        if (shouldOverride) {
+          // Create an instance and see what toString() returns
+          clazz.newInstance().toString();
+        }
+        // The overridden version of the class should return "hi". Make sure
+        // it does only if we are expecting to have loaded the overridden version.
+        assertTrue("hi".equals(s) == shouldOverride);
+    }
+
+    /**
+     * Asserts that given class has the expected defining loader.
+     */
+    static void testLoader(Class<?> clazz, ClassLoader expected) {
+        ClassLoader loader = clazz.getClassLoader();
+        if (loader != expected) {
+            throw new RuntimeException(clazz + " loaded by " + loader + ", expected " + expected);
+        }
+    }
+
+    static void assertTrue(boolean expr) {
+        assertTrue(expr, "");
+    }
+
+    static void assertTrue(boolean expr, String msg) {
+        if (!expr)
+            throw new RuntimeException("assertion failed: " + msg);
+    }
+}