Reduce test stress

[nomisRev]

Reduced the stress of our test suite by 10x by reducing the iterations to 100 instead of 1000.

This has shaved off ~ 7minutes on my local machine, while still covering all edgeCases.
There are two implementations here based on Kotest in Arrow Fx Coroutines, and KotlinTest in the rest.
We should push this change down to Arrow Core Test, so we can also configure iterations for law testing.

Proposed follow up work

Ideally, we'd decouple property testing from Kotest so:

-fun <A> Monoid<A>.monoidLeftIdentity(GEN: Gen<A>, EQ: Eq<A>): Unit =
+fun <A> Monoid<A>.monoidLeftIdentity(EQ: Eq<A>): Boolean =
-  forAll(GEN) { a ->
    (empty().combine(a)).equalUnderTheLaw(a, EQ)
-  }

This allows for more flexibility as you could plug it into both KotlinTest & Kotest and that simply becomes a integration instead of hard-coupled as it is today.

This also decouples the property testing from the law definition, and would allow us to easily control test strategy by the caller.

[JorgeCastilloPrz]

I know this is a hard to answer question but, how many iterations are okay to ensure code integrity? Could 100 iterations be too low to test an acceptable amount of edge cases?

[nomisRev]

@JorgeCastilloPrz Kotest checks that you have enough iterations to cover all edgeCases, so we're guaranteed to cover all edgeCases + iterations - edgeCases.size random values.

https://github.com/kotest/kotest/blob/master/kotest-property/src/commonMain/kotlin/io/kotest/property/internal/proptest.kt#L17

I just double checked for KotlinTest, and it doesn't have the same assurance but we need to refactor to Kotest asap since we're a version behind now.

[aballano]

I'm wondering if this is compatible with arrow-kt/arrow-core#105 somehow?

[nomisRev]

@aballano it's definitely combine-able with arrow-kt/arrow-core#105, but I feel like we should come up with a strategy that also incorporates upgrading to kotest.