--- /dev/null	2016-08-07 17:48:30.000000000 -0700
+++ new/langtools/test/tools/javac/modules/PatchModulesTest.java	2016-08-07 17:48:30.000000000 -0700
@@ -0,0 +1,127 @@
+/*
+ * Copyright (c) 2016, 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.
+ */
+
+/*
+ * @test
+ * @bug 8160489
+ * @summary tests for --patch-modules
+ * @library /tools/lib
+ * @modules
+ *      jdk.compiler/com.sun.tools.javac.api
+ *      jdk.compiler/com.sun.tools.javac.file
+ *      jdk.compiler/com.sun.tools.javac.main
+ * @build toolbox.ToolBox toolbox.JavacTask toolbox.ModuleBuilder ModuleTestBase
+ * @run main PatchModulesTest
+ */
+
+import java.io.File;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.lang.reflect.Field;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import javax.tools.JavaFileObject;
+import javax.tools.ToolProvider;
+
+import com.sun.source.util.JavacTask;
+import com.sun.tools.javac.api.JavacTool;
+import com.sun.tools.javac.file.BaseFileManager;
+import com.sun.tools.javac.file.JavacFileManager;
+import com.sun.tools.javac.file.Locations;
+
+import static java.util.Arrays.asList;
+
+
+public class PatchModulesTest extends ModuleTestBase {
+
+    public static void main(String... args) throws Exception {
+        PatchModulesTest t = new PatchModulesTest();
+        t.init();
+        t.runTests();
+    }
+
+    private static String PS = File.pathSeparator;
+
+    void init() throws IOException {
+        tb.createDirectories("a", "b", "c", "d", "e");
+        tb.writeJavaFiles(Paths.get("."), "class C { }");
+    }
+
+    @Test
+    public void testSimple(Path base) throws Exception {
+        test(asList("java.base=a"),
+            "{java.base=[a]}");
+    }
+
+    @Test
+    public void testPair(Path base) throws Exception {
+        test(asList("java.base=a", "java.compiler=b"),
+            "{java.base=[a], java.compiler=[b]}");
+    }
+
+    @Test
+    public void testMultiple(Path base) throws Exception {
+        test(asList("java.base=a:b"),
+            "{java.base=[a, b]}");
+    }
+
+    @Test
+    public void testLastOneWins(Path base) throws Exception {
+        test(asList("java.base=a", "java.compiler=b", "java.base=c"),
+            "{java.base=[c], java.compiler=[b]}");
+    }
+
+    void test(List<String> patches, String expect) throws Exception {
+        JavacTool tool = (JavacTool) ToolProvider.getSystemJavaCompiler();
+        StringWriter sw = new StringWriter();
+        try (PrintWriter pw = new PrintWriter(sw)) {
+            JavacFileManager fm = tool.getStandardFileManager(null, null, null);
+            List<String> opts = patches.stream()
+                .map(p -> "--patch-module=" + p.replace(":", PS))
+                .collect(Collectors.toList());
+            Iterable<? extends JavaFileObject> files = fm.getJavaFileObjects("C.java");
+            JavacTask task = tool.getTask(pw, fm, null, opts, null, files);
+
+            Field locationsField = BaseFileManager.class.getDeclaredField("locations");
+            locationsField.setAccessible(true);
+            Object locations = locationsField.get(fm);
+
+            Field patchMapField = Locations.class.getDeclaredField("patchMap");
+            patchMapField.setAccessible(true);
+            Map<?,?> patchMap = (Map<?,?>) patchMapField.get(locations);
+            String found = patchMap.toString();
+
+            if (!found.equals(expect)) {
+                tb.out.println("Expect: " + expect);
+                tb.out.println("Found:  " + found);
+                error("output not as expected");
+            }
+        }
+    }
+}
+