[jsinterp] Mozilla-central test first try

test/test_jsinterp_parser.py

@@ -547,6 +547,31 @@ class TestJSInterpreterParser(unittest.TestCase):
                ]
         self.assertEqual(list(jsi.statements()), ast)
 
+    def test_unshift(self):
+        # https://hg.mozilla.org/mozilla-central/file/tip/js/src/tests/ecma_5/Array/unshift-01.js
+        jsi = JSInterpreter(
+            '''var MAX_LENGTH = 0xffffffff;
+
+            var a = {};
+            a.length = MAX_LENGTH + 1;
+            assertEq([].unshift.call(a), MAX_LENGTH);
+            assertEq(a.length, MAX_LENGTH);
+
+            function testGetSet(len, expected) {
+                var newlen;
+                var a = { get length() { return len; }, set length(v) { newlen = v; } };
+                var res = [].unshift.call(a);
+                assertEq(res, expected);
+                assertEq(newlen, expected);
+            }
+
+            testGetSet(0, 0);
+            testGetSet(10, 10);
+            testGetSet("1", 1);
+            testGetSet(null, 0);
+            testGetSet(MAX_LENGTH + 2, MAX_LENGTH);
+            testGetSet(-5, 0);''')
+        jsi.statements()
 
 if __name__ == '__main__':
     unittest.main()