--- old/test/hotspot/jtreg/runtime/cds/appcds/PackageSealing.java	2020-06-24 22:02:43.303441772 +0000
+++ new/test/hotspot/jtreg/runtime/cds/appcds/PackageSealing.java	2020-06-24 22:02:42.377419184 +0000
@@ -29,6 +29,7 @@
  * @library /test/lib
  * @compile test-classes/C1.java
  * @compile test-classes/C2.java
+ * @compile test-classes/C3.java
  * @compile test-classes/PackageSealingTest.java
  * @compile test-classes/Hello.java
  * @run driver PackageSealing
@@ -50,13 +51,31 @@
         // test shared package from -cp path
         TestCommon.testDump(jars, TestCommon.list(classList));
         OutputAnalyzer output;
-        output = TestCommon.exec(jars, "PackageSealingTest");
+        output = TestCommon.exec(jars, "PackageSealingTest",
+                                 "sealed/pkg/C1", "sealed", "pkg/C2", "notSealed");
         TestCommon.checkExec(output, "OK");
 
         // test shared package from -Xbootclasspath/a
         TestCommon.dump(helloJar, TestCommon.list(classList),
                         "-Xbootclasspath/a:" + appJar);
-        output = TestCommon.exec(helloJar, "-Xbootclasspath/a:" + appJar, "PackageSealingTest");
+        output = TestCommon.exec(helloJar, "-Xbootclasspath/a:" + appJar,
+                                 "PackageSealingTest",
+                                 "sealed/pkg/C1", "sealed", "pkg/C2", "notSealed");
         TestCommon.checkExec(output, "OK");
+
+        // Test loading of two classes from the same package from different jars.
+        // First loaded class is from a non-sealed package, the second loaded
+        // class is from the same package but sealed.
+        // The expected result is a SecurityException with a "sealing violation".
+        classList[1] = "sealed/pkg/C3"; // C3 is from a non-sealed package
+        String[] classList2 = {"sealed/pkg/C3", "sealed/pkg/C1", "PackageSealingTest"};
+        String nonSealedJar = ClassFileInstaller.writeJar("non_sealed.jar", "sealed/pkg/C3");
+        jars = helloJar + File.pathSeparator + nonSealedJar;
+        TestCommon.testDump(jars, TestCommon.list(classList2), "-XX:+TraceExceptions");
+        jars += File.pathSeparator + appJar;
+        output = TestCommon.exec(jars, "PackageSealingTest",
+                                 "sealed/pkg/C3", "notSealed", "sealed/pkg/C1", "sealed");
+        TestCommon.checkExec(output, "sealing violation: can't seal package sealed.pkg: already defined");
+
     }
 }