Slow test runs

[leibole]

🐛 Bug Report

The simplest test runs very slow. It takes 6 seconds for just a 'should render' test. Any additional logic/test cases adds significant time to this, so it's not just overhead. I heard that you can run hundreds of tests in seconds with jest and jsdom.

The thing is, whenever I'm in watch mode and click 'a' to run all tests after running for the first time, the test takes last than a second. However, after saving a file in the project (while in watch mode), or running 'yarn test'/'yarn test --runInBand' the simplest test take 6 seconds.

The project was created with Create react app.

To Reproduce

Steps to reproduce the behavior:

you can look at the repo with the project:
https://github.com/leibole/sheeping-schedule

Expected behavior

A clear and concise description of what you expected to happen.

Link to repl or repo (highly encouraged)

https://github.com/leibole/sheeping-schedule

Run npx envinfo --preset jest

Paste the results here:

npx: installed 1 in 3.73s

  System:
    OS: OS X Yosemite 10.10.5
    CPU: x64 Intel(R) Core(TM) i5-4260U CPU @ 1.40GHz
  Binaries:
    Node: 10.9.0 - /usr/local/bin/node
    Yarn: 1.9.4 - /usr/local/bin/yarn
    npm: 6.2.0 - /usr/local/bin/npm

[rogeliog]

Thanks for reporting, I think it is a dup of facebook/create-react-app#5304

[leibole]

Any suggestion how to overcome this? Downgrade jest maybe?

[github-actions]

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