Indivudual tests very fast but total time is always above 20sec

[nicewaytodoit]

I am trying to test simple javascript class withing React project:

Following packages installed:

    "enzyme": "^3.8.0",
    "enzyme-adapter-react-16": "^1.7.1",
    "jest": "^23.6.0",
    "jest-cli": "^23.6.0",
    "react-test-renderer": "^16.7.0",
    "redux-devtools-extension": "^2.13.7",
    "source-map-loader": "^0.2.4",

  System:
    OS: Windows 10
    CPU: (4) x64 Intel(R) Core(TM) m3-7Y30 CPU @ 1.00GHz
  Binaries:
    Node: 10.15.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.13.0 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
    npm: 6.4.1 - C:\Program Files\nodejs\npm.CMD

I am using default configuration without ejected scripts.

I am testing single file, without any React dependencies or taking snapshot or similar things that could potentially take long time to execute. But, repeatedly these are my test times:

 PASS  src/__tests__/shared/validation.test.js (13.991s)me: 'red' } ] }
  # Validation module :
    √ should have class of red (4ms)
    √ function Argument number should be 1 (1ms)
    # Checking fakeValidationFunction :
      ○ skipped 7 tests
    # Emails should be equal :
      √ should return True if 2 emails equal (78ms)
      √ should return False if 2 emails not equal (43ms)

Test Suites: 1 passed, 1 total
Tests:       7 skipped, 4 passed, 11 total
Snapshots:   0 total
Time:        20.043s

All tests are showing time less than 200ms in total.
But total times are showing 13.99s and 20s, so my question are is this due to VS Code bash terminal, or git-bash, or something else?

What are those 19.8 seconds ? And is there any way to speed this up?

[thymikee]

Jest spends quite a lot of time crawling and analysing your dependencies before it starts the test so they can be run fast later.

Here are related topics: #7110 #6694 #6783

Closing, because we're aware that there are some speed regressions and this issue doesn't provide any new information that would be useful.

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