1 files changed, 14 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/collections/Map-delete-size.js b/js/src/jit-test/tests/collections/Map-delete-size.js
new file mode 100644
index 0000000000..c2537e0dc1
--- /dev/null
+++ b/js/src/jit-test/tests/collections/Map-delete-size.js
@@ -0,0 +1,14 @@
+// map.delete(k) decrements the map size iff an entry was actually removed.
+
+var m = new Map();
+m.delete(3);
+assertEq(m.size, 0);
+m.set({}, 'ok');
+m.set(Math, 'ok');
+assertEq(m.size, 2);
+m.delete({});
+assertEq(m.size, 2);
+m.delete(Math);
+assertEq(m.size, 1);
+m.delete(Math);
+assertEq(m.size, 1);