Add Scala.js support

[sbrunk]

This is an attempt to add Scala.js support to scalacheck-toolbox so that downstream projects can use it for tests running on Scala.js.

It adds Scala.js support to the datetime combinators modules. I left support for magic out for now as it would require changes in how blns.txt gets loaded.

Note that I've added sbt-projectmatrix for sane cross-building but I had to remove sbt-modules along the way.

Fixes #25

[sbrunk]

It doesn't look like the check failure is related to my changes, but I'm not familiar enough with the project to know for sure.

[BenFradet]

LGTM 👍. Seems like the mdoc plugin now makes warnings fail the build. I'll try to fix it.

[BenFradet]

can you rebase against master, ci should be fixed

[BenFradet]

the warning which makes the build fails is related to scala 2.13.3

[codecov]

Codecov Report

Merging #166 into master will increase coverage by 0.71%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #166      +/-   ##
==========================================
+ Coverage   95.68%   96.40%   +0.71%     
==========================================
  Files          10       10              
  Lines         139      139              
  Branches        2        2              
==========================================
+ Hits          133      134       +1     
+ Misses          6        5       -1     

Impacted Files	Coverage Δ
...ysevendeg/scalacheck/datetime/instances/joda.scala	100.00% <ø> (ø)
...rtysevendeg/scalacheck/datetime/joda/GenJoda.scala	94.44% <ø> (ø)
...scalacheck/datetime/joda/granularity/package.scala	100.00% <ø> (ø)
...ala/com/fortysevendeg/scalacheck/magic/Magic.scala	100.00% <ø> (ø)
...ortysevendeg/scalacheck/datetime/GenDateTime.scala	100.00% <0.00%> (+20.00%)	⬆️

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[BenFradet]

LGTM 👍 , there is still this q though https://github.com/47degrees/scalacheck-toolbox/pull/166/files#r492057195

[sbrunk]

Running the tests now takes almost 2 hours compared to ~18 minutes before 🙀

The Scala.js tests run on node.js. Seems like they are by a magnitude slower especially on constrained CI runners.

[sbrunk]

Ok it seems like only genPickFromMap* in CombinatorProperties is crazy slow on JS. Would you mind if I reduce the number of required successful tests from 100000 to 10000 (only when running on Scala.js of course)?

scalacheck-toolbox/modules/scalacheck-toolbox-combinators/src/test/scala/com/fortysevendeg/scalacheck/combinators/CombinatorProperties.scala

Lines 26 to 27 in 9dc3e81

	override def overrideParameters(p: Test.Parameters): Test.Parameters =
	p.withMinSuccessfulTests(100000)

[BenFradet]

fine with me as long as it's only for js 👍

[BenFradet]

LGTM 👍

[fedefernandez]

LGTM!

[sbrunk]

Dear maintainers,
do you have plans to cut a release in the near future? I'd love to use this library in a downstream project but I depend on a published version with Scala.js support. Thanks a lot!

[BenFradet]

yes, we should be releasing 0.4.0 today 👍