Laws failure for Order[FiniteDuration]

[TimWSpence]

I got hit by this on #3747 (as certain as I can be that it's unrelated)

failing seed for order.antisymmetry eq is Ue31ofRHQVK9wcbnhBqISNebQdvZZhUREH6EgJBgjHB=
==> X cats.kernel.laws.Tests.Order[Duration]: order.antisymmetry eq 0.041s munit.FailException: /home/runner/work/cats/cats/kernel-laws/shared/src/test/scala/cats/kernel/laws/LawTests.scala:200
199: checkAll("Order[BigInt]", OrderTests[BigInt].order)
200: checkAll("Order[Duration]", OrderTests[Duration].order)
201: checkAll("Order[FiniteDuration]", OrderTests[FiniteDuration].order)

Failing seed: hzeHOUHfb3_7x_2BxKaJnuLQt8g8rW9F_NIqhIjY5eA=
You can reproduce this failure by adding the following override to your suite:

override val scalaCheckInitialSeed = "hzeHOUHfb3_7x_2BxKaJnuLQt8g8rW9F_NIqhIjY5eA="

Falsified after 93 passed tests.

Labels of failing property:
Expected: true
Received: false
ARG_0: 1224 hours
ARG_1: 51 days
ARG_2: org.scalacheck.GenArities$$Lambda$495/0x0000000800dcd108@aaedf00
at munit.Assertions.fail(Assertions.scala:261)
at munit.Assertions.fail$(Assertions.scala:255)
at munit.FunSuite.fail(FunSuite.scala:11)
at munit.ScalaCheckSuite.$anonfun$propToTry$4(ScalaCheckSuite.scala:104)
at scala.util.Try$.apply(Try.scala:213)
at munit.ScalaCheckSuite.propToTry(ScalaCheckSuite.scala:104)
at munit.ScalaCheckSuite.$anonfun$scalaCheckPropTransform$3(ScalaCheckSuite.scala:46)
at scala.concurrent.impl.Promise.liftedTree1$1(Promise.scala:33)
at scala.concurrent.impl.Promise.$anonfun$transform$1(Promise.scala:33)
at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:64)
at munit.Suite$$anon$1.execute(Suite.scala:26)
at scala.concurrent.impl.CallbackRunnable.executeWithValue(Promise.scala:72)
at scala.concurrent.impl.Promise$KeptPromise$Kept.onComplete(Promise.scala:372)
at scala.concurrent.impl.Promise$KeptPromise$Kept.onComplete$(Promise.scala:371)
at scala.concurrent.impl.Promise$KeptPromise$Successful.onComplete(Promise.scala:379)
at scala.concurrent.impl.Promise.transform(Promise.scala:33)
at scala.concurrent.impl.Promise.transform$(Promise.scala:31)
at scala.concurrent.impl.Promise$KeptPromise$Successful.transform(Promise.scala:379)
at munit.internal.FutureCompat$ExtensionFuture.transformCompat(FutureCompat.scala:16)
at munit.ScalaCheckSuite.$anonfun$scalaCheckPropTransform$2(ScalaCheckSuite.scala:48)
at munit.GenericTest.$anonfun$withBodyMap$1(GenericTest.scala:33)
at munit.MUnitRunner.$anonfun$runTestBody$1(MUnitRunner.scala:296)

[TimWSpence]

Actually I see this has been discussed previously in #3353.

I'm a bit confused by the law actually - it seems to me that it need not hold in general

type Cogen[A] = (A, Seed) => Seed //essentially

def antiSymmetryEq(x: A, y: A, f: A => A): IsEq[Boolean] =
   (!E.eqv(x, y) || E.eqv(f(x), f(y))) <-> true

This law relies upon the function f being well-defined (x == y => f x == f y), where equality is determined by Eq. But of course in Scala we can easily write ill-defined functions eg when pattern matching. And in fact the functions generated by the Cogen instance are exactly that - they will take too equivalent FiniteDurations (eg 51 days and 1224 hours) and generate different values. The alternative Cogen implementation in Scalacheck looks like the only correct definition to me

[larsrh]

Seems to be a duplicate of #3734.