Bug 1298414 - Properly handle resolve/reject callbacks on xray'd promises. r=bz,efaust

MozReview-Commit-ID: H9dppdKlRG6

dom/promise/tests/test_promise_xrays.html

@@ -229,6 +229,19 @@ function testResolve3() {
   ).then(nextTest);
 }
 
+function testResolve4() {
+  var p = new win.Promise((res, rej) => {});
+  Components.utils.getJSTestingFunctions().resolvePromise(p, 42);
+  p.then(
+    function(arg) {
+      is(arg, 42, "Resolving an Xray to a promise with TestingFunctions resolvePromise should work");
+    },
+    function(e) {
+      ok(false, "Resolving an Xray to a promise with TestingFunctions resolvePromise should not fail");
+    }
+  ).then(nextTest);
+}
+
 function testReject1() {
   var p = win.Promise.reject(5);
   ok(p instanceof win.Promise, "Promise.reject should return a promise");
@@ -242,6 +255,19 @@ function testReject1() {
   ).then(nextTest);
 }
 
+function testReject2() {
+  var p = new win.Promise((res, rej) => {});
+  Components.utils.getJSTestingFunctions().rejectPromise(p, 42);
+  p.then(
+    function(arg) {
+      ok(false, "Rejecting an Xray to a promise with TestingFunctions rejectPromise should trigger catch handler");
+    },
+    function(e) {
+      is(e, 42, "Rejecting an Xray to a promise with TestingFunctions rejectPromise should work");
+    }
+  ).then(nextTest);
+}
+
 function testThen1() {
   var p = win.Promise.resolve(5);
   var q = p.then((x) => x*x);
@@ -314,7 +340,9 @@ var tests = [
   testResolve1,
   testResolve2,
   testResolve3,
+  testResolve4,
   testReject1,
+  testReject2,
   testThen1,
   testThen2,
   testCatch1,

js/src/builtin/Promise.cpp

@@ -1039,8 +1039,11 @@ GetResolveFunctionFromPromise(PromiseObject* promise)
     if (rejectFunVal.isUndefined())
         return nullptr;
     JSObject* rejectFunObj = &rejectFunVal.toObject();
+
+    // We can safely unwrap it because all we want is to get the resolve
+    // function.
     if (IsWrapper(rejectFunObj))
-        rejectFunObj = CheckedUnwrap(rejectFunObj);
+        rejectFunObj = UncheckedUnwrap(rejectFunObj);
 
     if (!rejectFunObj->is<JSFunction>())
         return nullptr;

js/src/builtin/TestingFunctions.cpp

@@ -1493,6 +1493,60 @@ GetWaitForAllPromise(JSContext* cx, unsigned argc, Value* vp)
     return true;
 }
 
+static bool
+ResolvePromise(JSContext* cx, unsigned argc, Value* vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    if (!args.requireAtLeast(cx, "resolvePromise", 2))
+        return false;
+    if (!args[0].isObject() || !UncheckedUnwrap(&args[0].toObject())->is<PromiseObject>()) {
+        JS_ReportErrorASCII(cx, "first argument must be a maybe-wrapped Promise object");
+        return false;
+    }
+
+    RootedObject promise(cx, &args[0].toObject());
+    RootedValue resolution(cx, args[1]);
+    mozilla::Maybe<AutoCompartment> ac;
+    if (IsWrapper(promise)) {
+        promise = UncheckedUnwrap(promise);
+        ac.emplace(cx, promise);
+        if (!cx->compartment()->wrap(cx, &resolution))
+            return false;
+    }
+
+    bool result = JS::ResolvePromise(cx, promise, resolution);
+    if (result)
+        args.rval().setUndefined();
+    return result;
+}
+
+static bool
+RejectPromise(JSContext* cx, unsigned argc, Value* vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    if (!args.requireAtLeast(cx, "rejectPromise", 2))
+        return false;
+    if (!args[0].isObject() || !UncheckedUnwrap(&args[0].toObject())->is<PromiseObject>()) {
+        JS_ReportErrorASCII(cx, "first argument must be a maybe-wrapped Promise object");
+        return false;
+    }
+
+    RootedObject promise(cx, &args[0].toObject());
+    RootedValue reason(cx, args[1]);
+    mozilla::Maybe<AutoCompartment> ac;
+    if (IsWrapper(promise)) {
+        promise = UncheckedUnwrap(promise);
+        ac.emplace(cx, promise);
+        if (!cx->compartment()->wrap(cx, &reason))
+            return false;
+    }
+
+    bool result = JS::RejectPromise(cx, promise, reason);
+    if (result)
+        args.rval().setUndefined();
+    return result;
+}
+
 #else
 
 static const js::Class FakePromiseClass = {
@@ -4148,6 +4202,12 @@ static const JSFunctionSpecWithHelp TestingFunctions[] = {
 "getWaitForAllPromise(densePromisesArray)",
 "  Calls the 'GetWaitForAllPromise' JSAPI function and returns the result\n"
 "  Promise."),
+JS_FN_HELP("resolvePromise", ResolvePromise, 2, 0,
+"resolvePromise(promise, resolution)",
+"  Resolve a Promise by calling the JSAPI function JS::ResolvePromise."),
+JS_FN_HELP("rejectPromise", RejectPromise, 2, 0,
+"rejectPromise(promise, reason)",
+"  Reject a Promise by calling the JSAPI function JS::RejectPromise."),
 #else
     JS_FN_HELP("makeFakePromise", MakeFakePromise, 0, 0,
 "makeFakePromise()",