Skip importing the same class twice -- re-mastered

rhino/src/main/java/org/mozilla/javascript/ImporterTopLevel.java

@@ -219,7 +219,10 @@ private static void importClass(Scriptable scope, NativeJavaClass cl) {
         String s = cl.getClassObject().getName();
         String n = s.substring(s.lastIndexOf('.') + 1);
         Object val = scope.get(n, scope);
-        if (val != NOT_FOUND && val != cl) {
+        if (val != NOT_FOUND) {
+            if (val.equals(cl)) {
+                return; // do not redefine same class
+            }
             throw Context.reportRuntimeErrorById("msg.prop.defined", n);
         }
         // defineProperty(n, cl, DONTENUM);

tests/src/test/java/org/mozilla/javascript/tests/ImportClassTest.java

@@ -0,0 +1,110 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/** */
+package org.mozilla.javascript.tests;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.util.UUID;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.mozilla.javascript.Context;
+import org.mozilla.javascript.ContextFactory;
+import org.mozilla.javascript.ImporterTopLevel;
+import org.mozilla.javascript.NativeJavaClass;
+import org.mozilla.javascript.Script;
+import org.mozilla.javascript.Scriptable;
+import org.mozilla.javascript.ScriptableObject;
+import org.mozilla.javascript.UniqueTag;
+import org.mozilla.javascript.drivers.TestUtils;
+import org.mozilla.javascript.tools.shell.Global;
+import org.mozilla.javascript.tools.shell.ShellContextFactory;
+
+/**
+ * @author donnamalayeri
+ */
+public class ImportClassTest {
+
+    protected final Global global = new Global();
+
+    public ImportClassTest() {
+        global.init(contextFactory);
+    }
+
+    @Before
+    public void setUp() {
+        TestUtils.setGlobalContextFactory(contextFactory);
+    }
+
+    @After
+    public void tearDown() {
+        TestUtils.setGlobalContextFactory(null);
+    }
+
+    private ContextFactory contextFactory =
+            new ShellContextFactory() {
+                @Override
+                protected boolean hasFeature(Context cx, int featureIndex) {
+                    if (featureIndex == Context.FEATURE_ENHANCED_JAVA_ACCESS) return true;
+                    return super.hasFeature(cx, featureIndex);
+                }
+            };
+
+    @Test
+    public void importPackageAndClass() {
+        Object result =
+                runScript(
+                        "importPackage(java.util);\n"
+                                + "UUID.randomUUID();\n" // calls getPkgProperty("UUID", global,
+                                // false)
+                                + "importClass(java.util.UUID);\n"
+                                + "UUID.randomUUID();\n"); // calls getPkgProperty("UUID",
+        // NativeJavaPackage, true)
+        assertTrue(Context.jsToJava(result, UUID.class) instanceof UUID);
+    }
+
+    @Test
+    public void importInSameContext() {
+        Object result = runScript("importClass(java.util.UUID);UUID.randomUUID();");
+        assertTrue(Context.jsToJava(result, UUID.class) instanceof UUID);
+        result = runScript("importClass(java.util.UUID);UUID.randomUUID();");
+        assertTrue(Context.jsToJava(result, UUID.class) instanceof UUID);
+    }
+
+    @Test
+    public void importMultipleTimes() {
+        Utils.runWithAllModes(
+                cx -> {
+                    ScriptableObject sharedScope = cx.initStandardObjects();
+                    // sharedScope.sealObject(); // code below will try to modify sealed object
+
+                    Script script =
+                            cx.compileString(
+                                    "importClass(java.util.UUID);true", "TestScript", 1, null);
+
+                    for (int i = 0; i < 3; i++) {
+                        Scriptable scope = new ImporterTopLevel(cx);
+                        scope.setPrototype(sharedScope);
+                        scope.setParentScope(null);
+                        script.exec(cx, scope);
+                        assertEquals(UniqueTag.NOT_FOUND, sharedScope.get("UUID", sharedScope));
+                        assertTrue(scope.get("UUID", scope) instanceof NativeJavaClass);
+                    }
+                    return null;
+                });
+    }
+
+    private Object runScript(final String scriptSourceText) {
+
+        return contextFactory.call(
+                context -> {
+                    Script script = context.compileString(scriptSourceText, "", 1, null);
+                    Object exec = script.exec(context, global);
+                    return exec;
+                });
+    }
+}