Fix proxies for property assertions

lib/chai-as-promised.js

@@ -5,6 +5,7 @@ let checkError = require("check-error");
 module.exports = (chai, utils) => {
     const Assertion = chai.Assertion;
     const assert = chai.assert;
+    const proxify = utils.proxify;
 
     // If we are using a version of Chai that has checkError on it,
     // we want to use that version to be consistent. Otherwise, we use
@@ -36,6 +37,10 @@ module.exports = (chai, utils) => {
         }
     }
 
+    function proxifyIfSupported(assertion) {
+        return proxify === undefined ? assertion : proxify(assertion);
+    }
+
     function method(name, asserter) {
         utils.addMethod(Assertion.prototype, name, function () {
             assertIsAboutPromise(this);
@@ -46,7 +51,7 @@ module.exports = (chai, utils) => {
     function property(name, asserter) {
         utils.addProperty(Assertion.prototype, name, function () {
             assertIsAboutPromise(this);
-            return asserter.apply(this, arguments);
+            return proxifyIfSupported(asserter.apply(this, arguments));
         });
     }
 
@@ -272,7 +277,7 @@ module.exports = (chai, utils) => {
             );
         } else {
             Assertion.overwriteProperty(getterName, originalGetter => function () {
-                return doAsserterAsyncAndAddThen(originalGetter, this);
+                return proxifyIfSupported(doAsserterAsyncAndAddThen(originalGetter, this));
             });
         }
     });

test/proxy-guard.js

@@ -0,0 +1,79 @@
+"use strict";
+const chai = require("chai");
+const chaiAsPromised = require("..");
+
+chai.should();
+chai.use(chaiAsPromised);
+
+function shouldGuard(fn, msg) {
+    fn.should.throw("Invalid Chai property: " + msg);
+}
+
+describe("Proxy guard", () => {
+    const number = 42;
+    const promise = Promise.resolve(42);
+
+    before(function () {
+        if (typeof Proxy === "undefined" || typeof Reflect === "undefined" || chai.util.proxify === undefined) {
+            /* eslint-disable no-invalid-this */
+            this.skip();
+            /* eslint-enable no-invalid-this */
+        }
+    });
+
+    it("should guard against invalid property following `.should`", () => {
+        shouldGuard(() => number.should.pizza, "pizza");
+    });
+
+    it("should guard against invalid property following overwritten language chain", () => {
+        shouldGuard(() => number.should.to.pizza, "pizza");
+    });
+
+    it("should guard against invalid property following overwritten property assertion", () => {
+        shouldGuard(() => number.should.ok.pizza, "pizza");
+    });
+
+    it("should guard against invalid property following uncalled overwritten method assertion", () => {
+        shouldGuard(() => number.should.equal.pizza, "equal.pizza. See docs");
+    });
+
+    it("should guard against invalid property following called overwritten method assertion", () => {
+        shouldGuard(() => number.should.equal(number).pizza, "pizza");
+    });
+
+    it("should guard against invalid property following uncalled overwritten chainable method assertion", () => {
+        shouldGuard(() => number.should.a.pizza, "pizza");
+    });
+
+    it("should guard against invalid property following called overwritten chainable method assertion", () => {
+        shouldGuard(() => number.should.a("number").pizza, "pizza");
+    });
+
+    it("should guard against invalid property following `.eventually`", () => {
+        shouldGuard(() => promise.should.eventually.pizza, "pizza");
+    });
+
+    it("should guard against invalid property following `.fulfilled`", () => {
+        shouldGuard(() => promise.should.fulfilled.pizza, "pizza");
+    });
+
+    it("should guard against invalid property following `.rejected`", () => {
+        shouldGuard(() => promise.should.rejected.pizza, "pizza");
+    });
+
+    it("should guard against invalid property following called `.rejectedWith`", () => {
+        shouldGuard(() => promise.should.rejectedWith(42).pizza, "pizza");
+    });
+
+    it("should guard against invalid property following uncalled `.rejectedWith`", () => {
+        shouldGuard(() => promise.should.rejectedWith.pizza, "rejectedWith.pizza. See docs");
+    });
+
+    it("should guard against invalid property following called `.become`", () => {
+        shouldGuard(() => promise.should.become(42).pizza, "pizza");
+    });
+
+    it("should guard against invalid property following uncalled `.become`", () => {
+        shouldGuard(() => promise.should.become.pizza, "become.pizza. See docs");
+    });
+});