Add fuzzing based tests in Jest (retry PR8012)

[dubzzz]

Summary

Following discussions with @jeysal and @SimenB in the PR #7938, I open a PR to add property based tests into the CI of Jest.

In a nutshell what it property based testing:

Property based can be classified as being some kind of fuzzing technic. The need for such technic comes from the fact that it is difficult and barely impossible to cover all the edge cases a code can have with classical unit-tests (so called example based tests).

Property based framework relies on assessing whether a property stays true for any valid inputs. It can be summarized by the following mathematical statement:

for all (x, y, ...)
such as precondition(x, y, ...) holds
property(x, y, ...) is true

In case of failure, it is able to reduce the randomly generated x, y to smaller entries to be more human readable.

[SimenB]

We've actually had a failure on ci with the same error after reverting. So I think we're probably pretty close to some limit, and this just pushed us over. Not sure how to best debug this

[dubzzz]

In a way, it's pretty reassuring for this PR, but indeed the memory issue in CI is a pretty blocking issue :/

Did you try to play with --max_old_space_size flag in node?

[SimenB]

No, haven't done anything with it

[dubzzz]

According to nodejs/node#7937 (comment) which references https://github.com/nodejs/node/blob/ec02b811a8a5c999bab4de312be2d732b7d9d50b/deps/v8/src/heap/heap.cc#L82, the size for a 64bits system would be 1400 MB = 700 * ((64/8) / 4) MB

[dubzzz]

It happened again :'(

[dubzzz]

@SimenB Can't we tweak the number of workers to use in the case of test-jest-circus?

It seems to have fixed a similar issue #5239

[SimenB]

It shouldn't need any different config than the other runs with jasmine. But feel free to tweak the -w flag

[codecov-io]

Codecov Report

Merging #8164 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #8164   +/-   ##
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  Coverage    62.3%   62.3%           
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  Files         265     265           
  Lines       10473   10473           
  Branches     2542    2542           
======================================
  Hits         6525    6525           
  Misses       3366    3366           
  Partials      582     582

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[scotthovestadt]

LGTM

[jeysal]

LGTM, @SimenB are there still concerns about memory usage making CI flaky?

[SimenB]

This has probably been alleviated by @scotthovestadt's work.

Great stuff, thanks again @dubzzz! (I'll respond to your RFC when I'm able to get my head above water, I feel bad for letting it linger 😞)

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