Fix double-resolving for misbehaved promises (#75).

See #76 for some discussion. The fix credit goes to @ForbesLindesay.
kriskowal · Jul 25, 2012 · e21707b · e21707b
1 parent 1633b11
commit e21707b
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Showing 2 changed files with 28 additions and 4 deletions.
diff --git a/q.js b/q.js
@@ -887,20 +887,27 @@ function when(value, fulfilled, rejected) {
 
     nextTick(function () {
         resolve(value).promiseSend("when", function (value) {
-            if (done) {
-                return;
-            }
-            done = true;
             resolve(value).promiseSend("when", function (value) {
+                if (done) {
+                    return;
+                }
+                done = true;
+
                 deferred.resolve(_fulfilled(value));
             }, function (exception) {
+                if (done) {
+                    return;
+                }
+                done = true;
+
                 deferred.resolve(_rejected(exception));
             });
         }, function (exception) {
             if (done) {
                 return;
             }
             done = true;
+
             deferred.resolve(_rejected(exception));
         });
     });

diff --git a/spec/q-spec.js b/spec/q-spec.js
@@ -1110,5 +1110,22 @@ describe("possible regressions", function () {
         });
     });
 
+    describe("gh-75", function () {
+        it("does not double-resolve misbehaved promises", function () {
+            var badPromise = Q.makePromise({
+                post: function () { return "hello"; }
+            });
+
+            var resolutions = 0;
+            function onResolution() {
+                ++resolutions;
+            }
+
+            return Q.when(badPromise, onResolution, onResolution).then(function () {
+                expect(resolutions).toBe(1);
+            });
+        });
+    });
+
 });