1 files changed, 68 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/basic/object-assign-plain-cache.js b/js/src/jit-test/tests/basic/object-assign-plain-cache.js
new file mode 100644
index 0000000000..8c6c163857
--- /dev/null
+++ b/js/src/jit-test/tests/basic/object-assign-plain-cache.js
@@ -0,0 +1,68 @@
+// The cache lookup must happen after ensuring there are no dense elements.
+function testNewDenseElement() {
+    var from = {x: 1, y: 2, z: 3};
+
+    for (var i = 0; i < 10; i++) {
+        if (i === 6) {
+            from[0] = 1;
+        }
+        var to = Object.assign({}, from);
+        if (i >= 6) {
+            assertEq(JSON.stringify(to), '{"0":1,"x":1,"y":2,"z":3}');
+        } else {
+            assertEq(JSON.stringify(to), '{"x":1,"y":2,"z":3}');
+        }
+    }
+}
+testNewDenseElement();
+
+// The cache lookup must happen after ensuring there are non-writable
+// properties on the proto chain.
+function testProtoNonWritable() {
+    var proto = {x: 1};
+    var from = {x: 1, y: 2, z: 3};
+
+    for (var i = 0; i < 10; i++) {
+        if (i === 6) {
+            Object.freeze(proto);
+        }
+
+        var to = Object.create(proto);
+        var ex = null;
+        try {
+            Object.assign(to, from);
+        } catch (e) {
+            ex = e;
+        }
+
+        assertEq(ex instanceof TypeError, i > 5);
+
+        if (i <= 5) {
+            assertEq(JSON.stringify(to), '{"x":1,"y":2,"z":3}');
+        } else {
+            assertEq(JSON.stringify(to), '{}');
+        }
+    }
+}
+testProtoNonWritable();
+
+function testDictionary1() {
+    var from = {a: 1, b: 2, c: 3};
+    delete from.a;
+    for (var i = 0; i < 10; i++) {
+        var to = Object.assign({}, from);
+        assertEq(JSON.stringify(to), '{"b":2,"c":3}');
+    }
+}
+testDictionary1();
+
+function testDictionary2() {
+    var from = {a: 1, b: 2, c: 3};
+    delete from.a;
+    from.a = 4;
+    for (var i = 0; i < 10; i++) {
+        var to = Object.assign({}, from);
+        assertEq(JSON.stringify(to), '{"b":2,"c":3,"a":4}');
+    }
+}
+testDictionary2();