Cancelling RSVP.resolve should also cancel thenable.

dist/commonjs/rsvp/resolve.js

@@ -3,7 +3,17 @@ var Promise = require("./promise").Promise;
 
 function resolve(thenable) {
   return new Promise(function(resolve, reject) {
-    resolve(thenable);
+    if (typeof thenable === "object" && thenable !== null) {
+      var then = thenable.then;
+      if ((then !== undefined) && (typeof then === "function")) {
+        return then.apply(thenable, [resolve, reject]);
+      }
+    }
+    return resolve(thenable);
+  }, function () {
+    if ((thenable !== undefined) && (thenable.cancel !== undefined)) {
+      thenable.cancel();
+    }
   });
 }
 

dist/rsvp-2.0.4.amd.js

@@ -828,7 +828,17 @@ define("rsvp/resolve",
 
     function resolve(thenable) {
       return new Promise(function(resolve, reject) {
-        resolve(thenable);
+        if (typeof thenable === "object" && thenable !== null) {
+          var then = thenable.then;
+          if ((then !== undefined) && (typeof then === "function")) {
+            return then.apply(thenable, [resolve, reject]);
+          }
+        }
+        return resolve(thenable);
+      }, function () {
+        if ((thenable !== undefined) && (thenable.cancel !== undefined)) {
+          thenable.cancel();
+        }
       });
     }
 

dist/rsvp-2.0.4.js

@@ -865,7 +865,17 @@ define("rsvp/resolve",
 
     function resolve(thenable) {
       return new Promise(function(resolve, reject) {
-        resolve(thenable);
+        if (typeof thenable === "object" && thenable !== null) {
+          var then = thenable.then;
+          if ((then !== undefined) && (typeof then === "function")) {
+            return then.apply(thenable, [resolve, reject]);
+          }
+        }
+        return resolve(thenable);
+      }, function () {
+        if ((thenable !== undefined) && (thenable.cancel !== undefined)) {
+          thenable.cancel();
+        }
       });
     }
 

lib/rsvp/resolve.js

@@ -2,7 +2,17 @@ import { Promise } from "./promise";
 
 function resolve(thenable) {
   return new Promise(function(resolve, reject) {
-    resolve(thenable);
+    if (typeof thenable === "object" && thenable !== null) {
+      var then = thenable.then;
+      if ((then !== undefined) && (typeof then === "function")) {
+        return then.apply(thenable, [resolve, reject]);
+      }
+    }
+    return resolve(thenable);
+  }, function () {
+    if ((thenable !== undefined) && (thenable.cancel !== undefined)) {
+      thenable.cancel();
+    }
   });
 }
 

test/tests/extension_test.js

@@ -1335,9 +1335,10 @@ describe("RSVP extensions", function() {
 
         wrapped = RSVP.resolve(thenable);
 
-        assert(accessCount === 1);
-
-        done();
+        setTimeout(function() {
+          assert(accessCount === 1);
+          done();
+        }, 20);
       });
 
       specify("2.2 If retrieving the property x.then results in a thrown exception e, reject promise with e as the reason.", function(done){
@@ -1532,6 +1533,23 @@ describe("RSVP extensions", function() {
         assert(callCount === 0, 'expected async, was sync');
       });
     });
+
+    describe("4. If x is a promise, ", function(){
+      specify("cancel will also cancel x.", function(done){
+        var thenable, wrapped;
+
+        thenable = RSVP.delay();
+
+        wrapped = RSVP.resolve(thenable);
+
+        thenable.fail(function(error){
+          assert(error instanceof RSVP.CancellationError, 'expected CancellationError');
+          done();
+        });
+
+        wrapped.cancel();
+      });
+    });
   });
 });