Fix ClassCastException when using StringBuilder/Buffer mozilla#496

testsrc/org/mozilla/javascript/tests/Issue1206Test.java

@@ -0,0 +1,36 @@
+/* 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 org.junit.Test;
+import org.mozilla.javascript.Context;
+import org.mozilla.javascript.Scriptable;
+
+/** Tests the ConsString class to ensure it properly supports String, StringBuffer and StringBuilder. */
+public class Issue1206Test {
+    @Test
+    public void testConsStringUsingString() {
+        Context cx = Context.enter();
+        Scriptable scope = cx.initStandardObjects(null);
+        scope.put("var1", scope, "hello");
+        cx.evaluateString(scope, "var1 = var1 + ' world'", "test", 1, null);
+    }
+
+    @Test
+    public void testConsStringUsingStringBuffer() {
+        Context cx = Context.enter();
+        Scriptable scope = cx.initStandardObjects(null);
+        scope.put("var1", scope, new StringBuffer("hello"));
+        cx.evaluateString(scope, "var1 = var1 + ' world'", "test", 1, null);
+    }
+
+    @Test
+    public void testConsStringUsingStringBuilder() {
+        Context cx = Context.enter();
+        Scriptable scope = cx.initStandardObjects(null);
+        scope.put("var1", scope, new StringBuilder("hello"));
+        cx.evaluateString(scope, "var1 = var1 + ' world'", "test", 1, null);
+    }
+}