25+5 Clock - Test 8 fails locally but passes on codepen

I normally develop my projects locally and then copy them over to either codepen.io or codesandbox.io when I have finished.

It has taken me a while to burn down the failures on the 25+5 clock test but I had finally got it down to one failure on test 8. The test reads:

I can see an element with corresponding id=“time-left”. NOTE: Paused or running, the value in this field should always be displayed in mm:ss format (i.e. 25:00).

With a corresponding error message of:

Timeout of 2000ms exceeded. For async tests and hooks, ensure “done()” is called; if returning a Promise, ensure it resolves.

I read through a lot of forum posts looking for a solution but to no avail, so I thought I’d make one myself. When I copied my code over to codepen and ran it there however all of the tests pass.

Obviously I am happy that I have completed this aspect of the challenge (I still need to tidy up the formatting) but I would still like to get it working locally before I hand it in. I created a React project via npx create-react-app and edit using VS Code. I have tried running locally using both Chrome and Firefox. I am just wondering if anyone has seen anything like this before?


It is probably because development build is not optimized for performance.

I had a similar problem with this challenge while developing but once in production it went away :wink:

Could be, this sounds like a possible explanation.