Electron slows down dramatically when tests are run multiple times

[marinakuranda]

It's a bug

Current behavior:

When I run the same test 200 times in Electron, both headless and headed, at some point tests start to drag. This usually happens after 100~ runs, with every test it takes longer and longer before the timeout and a failure.
A really short simple test like for example just opening a page will not slow down.
But a reasonably simple test that consists of about 50 lines will.
Tested on different tests and environments, so the issue is not isolated to the setup.
Everything works just fine in headed Chrome (not to confuse with GUI, which is not intended for longer runs, see comments in #431 )

Mostly concerned about Electron headless mode rather than headed, as Electron is the only available browser for the headless currently. (#832 is still open as of now)

Desired behavior:

Tests should not slow down in headless Electron when run multiple times.

Steps to reproduce: (app code and test code)

Run the test "pdp-mobile.spec.js" via npm run open, it will run for 200 times.
See that the initial run time per test is about 15 sec.

See that around the 150th time the test starts to slow down drastically, reaching the run time per test up to almost 4 min.

Once the test starts to slow down, only a very generous defaultCommandTimeout of 20 sec is enough to stop the tests from failing due to the timing out.

Link to the repository: https://github.com/marinakuranda/cypress-bug-example

Versions

Cypress 3.4.1
OS Linux Manjaro, also reproduced on Windows 7.
The issue is isolated to Electron, when run in Chrome all is ok.

[joskoskilj]

Any updates on this?

[jennifer-shehane]

This example is not reproducible as is. The url visiting 404s. Although I suspect it has something to do with this performance issue or something similar that we've seen with multiple Cypress commands in a single test. #6783