1 files changed, 41 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/basic/for-in-proto-properties.js b/js/src/jit-test/tests/basic/for-in-proto-properties.js
new file mode 100644
index 0000000000..a8f2279c4e
--- /dev/null
+++ b/js/src/jit-test/tests/basic/for-in-proto-properties.js
@@ -0,0 +1,41 @@
+function testNonEnumerableVisited() {
+    // Non-enumerable properties must still be included in the duplicate-property
+    // checking.
+
+    var proto1 = Object.create(null);
+    Object.defineProperty(proto1, "x", {enumerable: true, value: 1});
+
+    var proto2 = Object.create(proto1);
+    Object.defineProperty(proto2, "x", {enumerable: false, value: 1});
+
+    for (var p in proto2) {
+        throw "Shouldn't enumerate any properties";
+    }
+
+    var o = Object.create(proto2);
+    for (var p in o) {
+        throw "Shouldn't enumerate any properties";
+    }
+}
+testNonEnumerableVisited();
+
+function testEnumerableOnProto() {
+    var iter = o => {
+        var props = [];
+        for (var p in o) { props.push(p); }
+        return props;
+    };
+
+    // Test dense elements on the proto chain are included.
+    var props = iter(Object.create({0: 1}));
+    assertEq(JSON.stringify(props), '["0"]');
+
+    // Test typed array elements on the proto chain are included.
+    props = iter(Object.create(new Int32Array(2)));
+    assertEq(JSON.stringify(props), '["0","1"]');
+
+    // Test sparse elements on the proto chain are included.
+    props = iter(Object.create({1234567: 1}));
+    assertEq(JSON.stringify(props), '["1234567"]');
+}
+testEnumerableOnProto();