1 files changed, 47 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/for-of/strings.js b/js/src/jit-test/tests/for-of/strings.js
new file mode 100644
index 0000000000..1dab295b01
--- /dev/null
+++ b/js/src/jit-test/tests/for-of/strings.js
@@ -0,0 +1,47 @@
+// for-of works on strings and String objects.
+
+load(libdir + "string.js");
+
+function test(s, expectedCodePoints) {
+    var copy = '';
+    var codepoints = 0;
+    var singleHighSurrogate = false;
+    for (var v of s) {
+        assertEq(typeof v, 'string');
+        assertEq(v.length, isSurrogatePair(v) ? 2 : 1);
+        assertEq(false, singleHighSurrogate && isLowSurrogate(v));
+        copy += v;
+        codepoints += 1;
+        singleHighSurrogate = !isSurrogatePair(v) && isHighSurrogate(v);
+    }
+    assertEq(copy, String(s));
+    assertEq(codepoints, expectedCodePoints);
+}
+
+test('', 0);
+test('abc', 3);
+test('a \0 \ufffe \ufeff', 7);
+
+// Non-BMP characters are generally passed to JS in UTF-16, as surrogate pairs.
+// ES6 requires that such pairs be treated as a single code point in for-of.
+test('\ud808\udf45', 1);
+
+// Also test invalid surrogate pairs:
+// (1) High surrogate not followed by low surrogate
+test('\ud808', 1);
+test('\ud808\u0000', 2);
+// (2) Low surrogate not preceded by high surrogate
+test('\udf45', 1);
+test('\u0000\udf45', 2);
+// (3) Low surrogate followed by high surrogate
+test('\udf45\ud808', 2);
+
+test(new String(''), 0);
+test(new String('abc'), 3);
+test(new String('a \0 \ufffe \ufeff'), 7);
+test(new String('\ud808\udf45'), 1);
+test(new String('\ud808'), 1);
+test(new String('\ud808\u0000'), 2);
+test(new String('\udf45'), 1);
+test(new String('\u0000\udf45'), 2);
+test(new String('\udf45\ud808'), 2);