Merge pull request #38 from Lemoncode/feature/#37_enhance_promise_chaining

#37 Return input args in promise chaining

Author: nasdan

src/trackPromise.js

@@ -17,10 +17,8 @@ export const trackPromise = (promise, area) => {
   const promiseInProgress = anyPromiseInProgress(area);
   emitter.emit(promiseCounterUpdateEventId, promiseInProgress, area);
 
-  promise
-    .then(() => decrementPromiseCounter(area),
-      () => decrementPromiseCounter(area)
-    );
+  const onResolveHandler = () => decrementPromiseCounter(area);
+  promise.then(onResolveHandler, onResolveHandler);
 
   return promise;
 };

src/trackPromise.test.js

@@ -86,6 +86,23 @@ describe('trackPromise', () => {
         done();
       });
     });
+
+    // Promise chaining working properly.
+    it('Promise returned must handle transparently the result when resolved', (done) => {
+      // Arrange
+      const expectedPromiseResult = "promise result";
+      const promise = Promise.resolve(expectedPromiseResult);
+
+      // Act
+      const trackedPromise = trackPromise(promise);
+
+      // Assert
+      trackedPromise.then((trackedPromiseResult) => {
+        expect(trackedPromiseResult).toEqual(expectedPromiseResult);
+        done();
+      });
+    });
+
   });
 
   describe('using custom area', () => {