Selenium webdriver test 100% pass locally, 100% fails on VSTS server

Issue

currently in my 2nd week of trying to work out why a certain test runs perfectly locally but fails when being kicked off by a VSTS agent.

Program flow:

• Select an row from a table
• Click Verify button
• CSS overlay darkens the screen, spinner in the middle
• Toaster pop up in the bottom left saying Verification starting
• About 1.5 minutes of time passes, spinner spins
• CSS overlay removed
• Toaster pop up bottom left, successful verification

I have screenshots and debug output on everystep of the way and the failure is at the "Waiting for CSS overlay to be removed" stage. It times out waiting for it, now matter how long the timeout.

Screenshot shows the CSS overlay and spinner still spinning even though the verification process completed successfully. Its almost as if it's stuck in time.

Scenarios and results:

• Run from Local Visual Studio - PASS
• VSTS Agent - FAIL
• Manually run on VSTS Agent by remoting in and passing the exact commandline as the build - PASS (This is what infuriates me!!)
• Downgrading / upgrading Webdriver - no difference
• Headless / full mode - no difference
• Using different types of waits - no difference
• Waiting for Toaster pop ups instead of CSS - no difference

Solution

I'll answer my own question: We created a new agent which was an auto login. We watched the test run and pressed F12 and there, in the console, was an error.

It was trying to trim() on the username, the test account looked like it had a username but I guess it didn't really. So the system, when run by the agent, was throwing an error and not handling it.

Handled the error and everything went through swimmingly. Very long and frustrating road to get to here! Hope this helps someone in the future.

Answered By - PeterG