1 files changed, 27 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/collections/WeakMap-constructor-duplicates.js b/js/src/jit-test/tests/collections/WeakMap-constructor-duplicates.js
new file mode 100644
index 0000000000..5e5f3a58e9
--- /dev/null
+++ b/js/src/jit-test/tests/collections/WeakMap-constructor-duplicates.js
@@ -0,0 +1,27 @@
+// When the argument to WeakMap contains a key multiple times, the last value
+// is retained.
+
+var k1 = {};
+var v1 = 42;
+var k2 = {};
+var v2 = 43;
+var k3 = {};
+var v3 = 44;
+var k4 = {};
+
+var wrong1 = 8;
+var wrong2 = 9;
+var wrong3 = 10;
+
+var arr = [[k1, wrong1], [k2, v2], [k3, wrong2], [k1, wrong3], [k3, v3], [k1, v1]];
+
+var m = new WeakMap(arr);
+
+assertEq(m.has(k1), true);
+assertEq(m.has(k2), true);
+assertEq(m.has(k3), true);
+assertEq(m.has(k4), false);
+assertEq(m.get(k1), v1);
+assertEq(m.get(k2), v2);
+assertEq(m.get(k3), v3);
+assertEq(m.get(k4), undefined);