From 97e0bc8e87f1caa68950e5e2f2ddd7865b3705f6 Mon Sep 17 00:00:00 2001
From: Berkeley Martinez <Berkeley@robotie.com>
Date: Mon, 12 Sep 2016 13:21:41 -0700
Subject: [PATCH] Feat(challenges): Adds the ability to test with async methods

---
 client/frame-runner.js | 59 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 48 insertions(+), 11 deletions(-)

diff --git a/client/frame-runner.js b/client/frame-runner.js
index e6e038a248..35cf7c9c43 100644
--- a/client/frame-runner.js
+++ b/client/frame-runner.js
@@ -3,6 +3,7 @@ document.addEventListener('DOMContentLoaded', function() {
   var frameId = window.__frameId;
   var frameReady = common[frameId + 'Ready$'] || { onNext() {} };
   var Rx = document.Rx;
+  var helpers = Rx.helpers;
   var chai = parent.chai;
   var source = document.__source;
 
@@ -37,32 +38,68 @@ document.addEventListener('DOMContentLoaded', function() {
       // add delay here for firefox to catch up
       .delay(200)
       /* eslint-disable no-unused-vars */
-      .map(({ text, testString }) => {
+      .flatMap(({ text, testString }) => {
         const assert = chai.assert;
       /* eslint-enable no-unused-vars */
         const newTest = { text, testString };
         let test;
+        let __result;
         try {
           /* eslint-disable no-eval */
+          // eval test string to actual JavaScript
+          // This return can be a function
+          // i.e. function() { assert(true, 'happy coding'); }
           test = eval(testString);
           /* eslint-enable no-eval */
           if (typeof test === 'function') {
-            // maybe sync/promise/observable
+
+            // we know that the test eval'ed to a function
+            // the function could expect a callback
+            // or it could return a promise/observable
+            // or it could still be sync
             if (test.length === 0) {
-              test();
+              // a function with length 0 means it expects 0 args
+              // We call it and store the result
+              // This result may be a promise or an observable or undefined
+              __result = test();
+            } else {
+              // if function takes arguments
+              // we expect it to be of the form
+              // function(cb) { /* ... */ }
+              // and callback has the following signature
+              // function(err) { /* ... */ }
+              __result = Rx.Observable.fromNodeCallback(test)();
             }
-            // callback test
-            if (test.length === 1) {
-              console.log('callback test');
+
+            if (helpers.isPromise(__result)) {
+              // turn promise into an observable
+              __result = Rx.Observable.fromPromise(__result);
             }
+          } else {
+            // test is not a function
+            // fill result with for compatibility
+            __result = Rx.Observable.of(null);
           }
         } catch (e) {
-          newTest.err = e.message + '\n' + e.stack;
+          // something threw an uncaught error
+          // we catch here and wrap it in an observable
+          __result = Rx.Observable.throw(e);
         }
-        if (!newTest.err) {
-          newTest.pass = true;
-        }
-        return newTest;
+        return __result
+          .map(() => {
+            // we don't need the result of a promise/observable/cb here
+            // all data asserts should happen further up the chain
+            // mark test as passing
+            newTest.pass = true;
+            return newTest;
+          })
+          .catch(err => {
+            // we catch the error here to prevent the error from bubbling up
+            // and collapsing the pipe
+            newTest.err = err.message + '\n' + err.stack;
+            // RxJS catch expects an observable as a return
+            return Rx.Observable.of(err);
+          });
       })
       // gather tests back into an array
       .toArray();