1 files changed, 46 insertions, 0 deletions
diff --git a/js/src/tests/non262/lexical-environment/unscopables-proxy.js b/js/src/tests/non262/lexical-environment/unscopables-proxy.js
new file mode 100644
index 0000000000..fcf241ee46
--- /dev/null
+++ b/js/src/tests/non262/lexical-environment/unscopables-proxy.js
@@ -0,0 +1,46 @@
+// Object operations are performed in the right order, as observed by proxies.
+
+let log = [];
+function LoggingProxyHandlerWrapper(name, handler={}) {
+    return new Proxy(handler, {
+        get(t, id) {
+            let method = handler[id];
+            return function (...args) {
+                log.push([name + "." + id, ...args.filter(v => typeof v !== "object")]);
+                if (method === undefined)
+                    return Reflect[id].apply(null, args);
+                return method.apply(this, args);
+            };
+        }
+    });
+}
+
+function LoggingProxy(name, target) {
+    return new Proxy(target, new LoggingProxyHandlerWrapper(name));
+}
+
+let proto = {x: 44};
+let proto_proxy = new LoggingProxy("proto", proto);
+let unscopables = {x: true};
+let unscopables_proxy = new LoggingProxy("unscopables", {x: true});
+let env = Object.create(proto_proxy, {
+    [Symbol.unscopables]: { value: unscopables_proxy }
+});
+let env_proxy = new LoggingProxy("env", env);
+
+let x = 11;
+function f() {
+    with (env_proxy)
+        return x;
+}
+
+assertEq(f(), 11);
+
+assertDeepEq(log, [
+    ["env.has", "x"],
+    ["proto.has", "x"],
+    ["env.get", Symbol.unscopables],
+    ["unscopables.get", "x"]
+]);
+
+reportCompare(0, 0);