From daed7ad5dd4c86ea88932d2e9ed8f184bb5a603b Mon Sep 17 00:00:00 2001
From: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>
Date: Mon, 15 Jun 2020 15:11:34 +0200
Subject: [PATCH] fix(client): ensure dom ready before testing (#39073)

jQuery challenges can fail seemingly at random. These changes should
prevent the race condition between a user's $( document ).ready() and
test evalution.
---
 client/src/client/frame-runner.js | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/client/src/client/frame-runner.js b/client/src/client/frame-runner.js
index 16da84efca3..ec0433b6fd1 100644
--- a/client/src/client/frame-runner.js
+++ b/client/src/client/frame-runner.js
@@ -59,8 +59,22 @@ async function initTestFrame(e = {}) {
       // eval test string to actual JavaScript
       // This return can be a function
       // i.e. function() { assert(true, 'happy coding'); }
-      // eslint-disable-next-line no-eval
-      const test = eval(testString);
+      const testPromise = new Promise((resolve, reject) =>
+        // To avoid race conditions, we have to run the test in a final
+        // document ready:
+        $(() => {
+          try {
+            // eslint-disable-next-line no-eval
+            const test = eval(testString);
+            resolve({ test });
+          } catch (err) {
+            reject({ err });
+          }
+        })
+      );
+      const { test, err } = await testPromise;
+      if (err) throw err;
+
       if (typeof test === 'function') {
         await test(e.getUserInput);
       }