1 files changed, 41 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/basic/assign-reuse-propmap.js b/js/src/jit-test/tests/basic/assign-reuse-propmap.js
new file mode 100644
index 0000000000..e78bddd20e
--- /dev/null
+++ b/js/src/jit-test/tests/basic/assign-reuse-propmap.js
@@ -0,0 +1,41 @@
+function testBasic() {
+    var o1 = {x: 1};
+    var o2 = {a: 1, b: 2, c: 3, x: 4, y: 5, z: 6};
+    for (var i = 0; i < 4; i++) {
+        var to1 = Object.assign({}, o1);
+        assertEq(JSON.stringify(to1), '{"x":1}');
+        var to2 = Object.assign({}, o2);
+        assertEq(JSON.stringify(to2), '{"a":1,"b":2,"c":3,"x":4,"y":5,"z":6}');
+    }
+}
+testBasic();
+
+// Target object's proto must not be changed by assign.
+function testProto() {
+    var from = {};
+    from.a = 1;
+    from.b = 2;
+    from.c = 3;
+    for (var i = 0; i < 5; i++) {
+        var to = Object.assign(Object.create(null), from);
+        assertEq(JSON.stringify(to), '{"a":1,"b":2,"c":3}');
+        assertEq(Object.getPrototypeOf(to), null);
+    }
+}
+testProto();
+
+// Target object's realm must not be changed by assign.
+function testRealm() {
+    var global = newGlobal({sameCompartmentAs: this});
+    var from = global.evaluate("({})");
+    from.a = 1;
+    from.b = 2;
+    from.c = 3;
+    for (var i = 0; i < 5; i++) {
+        var to = Object.assign({}, from);
+        assertEq(JSON.stringify(to), '{"a":1,"b":2,"c":3}');
+        assertEq(objectGlobal(to), this);
+        assertEq(Object.getPrototypeOf(to), Object.prototype);
+    }
+}
+testRealm();