1 files changed, 31 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/cacheir/string-concat-null-undef.js b/js/src/jit-test/tests/cacheir/string-concat-null-undef.js
new file mode 100644
index 0000000000..6ef75dc181
--- /dev/null
+++ b/js/src/jit-test/tests/cacheir/string-concat-null-undef.js
@@ -0,0 +1,31 @@
+function test() {
+  var nullUndefLhs = [
+    [null, "foo", "nullfoo"],
+    [null, "bar", "nullbar"],
+    [null, "123", "null123"],
+    [null, "", "null"],
+    [undefined, "abc", "undefinedabc"],
+    [undefined, "1", "undefined1"],
+    [undefined, "", "undefined"],
+    ["abc", "def", "abcdef"],
+  ];
+  for (var [lhs, rhs, expected] of nullUndefLhs) {
+    assertEq(lhs + rhs, expected);
+  }
+  var nullUndefRhs = [
+    ["foo", undefined, "fooundefined"],
+    ["bar", undefined, "barundefined"],
+    ["123", undefined, "123undefined"],
+    ["", undefined, "undefined"],
+    ["abc", null, "abcnull"],
+    ["1", null, "1null"],
+    ["", null, "null"],
+    ["abc", "def", "abcdef"],
+  ];
+  for (var [lhs, rhs, expected] of nullUndefRhs) {
+    assertEq(lhs + rhs, expected);
+  }
+}
+test();
+test();
+test();