chore(package): switch to Jest

[layershifter]

WIP

[layershifter]

@levithomason it's interesting, but Jest is much slower than our existing solution. I've pulled stardust and seen that there are same problems:

 PASS  test/specs/lib/eventStack/EventTarget-test.ts (8.016s)
 PASS  test/specs/lib/htmlInputPropsUtils-test.ts
 PASS  test/specs/lib/doesNodeContainClick-test.ts (11.209s)
 PASS  test/specs/lib/eventStack/eventStack-test.ts (11.271s)
 PASS  test/specs/lib/factories-test.tsx (11.314s)

I think that it's quite slow. Did I miss something?

[levithomason]

Strange, I have no idea. @davezuko?

[dvdzkwsk]

Maybe a Windows issue? The test suite runs in 8s for me on a cold start, and 4.75 on subsequent runs.

[layershifter]

SUIR

I will try to update tests for views fully and then will followup again.

Our existing suite is running 02:26: https://circleci.com/gh/Semantic-Org/Semantic-UI-React/5649
Current suite (/lib only) runs 00:54: https://circleci.com/gh/Semantic-Org/Semantic-UI-React/5644

Current suite (/lib and /views) locally:

Test Suites: 5 failed, 60 passed, 65 total
Tests:       13 failed, 1789 passed, 1802 total
Snapshots:   0 total
Time:        92.138s (01:32)

There are many failed tests, but it looks very poorly.

[layershifter]

Stardust

 PASS  test/specs/lib/doesNodeContainClick-test.ts (9.266s)
 PASS  test/specs/lib/factories-test.tsx (9.416s)

Test Suites: 24 passed, 24 total
Tests:       6 skipped, 351 passed, 357 total
Snapshots:   0 total
Time:        32.258s

Ubuntu 16.04
i7 2637m

Looks bad to me, too.

[layershifter]

I'm worried that after switching to Jest, our tests will be performed substantially longer.

---

If I omit Babel and write code/tests in raw JS, tests are running blazing fast. Looks like Babel has a cold start on each test 🤔

[thymikee]

This is the cause of slow tests, as they are run serially. Try to leverage number of cores you can use on your CI, try different ones, e.g. yarn test -w=4 for 4 parallel workers. Some CIs are better and some worse in using multiple cores, that's why you need to play with it a bit

[layershifter]

https://circleci.com/gh/Semantic-Org/Semantic-UI-React/5711

Removal of this option causes build failure. Also, microsoft/fluent-ui-react#53

[thymikee]

That's why I was talking about using certain number of workers, not all available (depending on CI, it can tell Jest it has even 128 cpus). You should be good to run jest without flags locally, as you probably have up to 8 cores and enough memory.

[codecov-io]

Codecov Report

Merging #2971 into master will decrease coverage by 32.28%.
The diff coverage is 85.03%.

@@             Coverage Diff             @@
##           master    #2971       +/-   ##
===========================================
- Coverage   99.96%   67.67%   -32.29%     
===========================================
  Files         163       76       -87     
  Lines        2743     1324     -1419     
  Branches        0      229      +229     
===========================================
- Hits         2742      896     -1846     
- Misses          1      428      +427

Impacted Files	Coverage Δ
src/views/Feed/FeedLabel.js	100% <ø> (ø)	⬆️
test/specs/commonTests/hasSubcomponents.js	100% <100%> (ø)
test/utils/consoleUtil.js	100% <100%> (ø)
test/specs/commonTests/hasValidTypings.js	100% <100%> (ø)
test/utils/componentInfo.js	100% <100%> (ø)
test/specs/commonTests/implementsClassNameProps.js	100% <100%> (ø)
test/setupTests.js	100% <100%> (ø)
test/specs/commonTests/classNameHelpers.js	100% <100%> (ø)
test/specs/commonTests/implementsCreateMethod.js	100% <100%> (ø)
test/specs/commonTests/hasUIClassName.js	100% <100%> (ø)
... and 189 more

---

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