How do I test laws for my semigroups?

[Daenyth]

The laws stuff appears to only contain SemigroupK stuff, but nothing for Semigroup (and also Monoid).

I can obviously write out the scalacheck by hand, but it would be nice if it integrated with the rest of the discipline-based stuff

[peterneyens]

The laws for type classes in cats-kernel like Semigroup and Monoid can be found in cats-kernel-laws.

Eg

import cats.kernel.laws.GroupLaws

checkAll("Int", GroupLaws[Int].semigroup)
checkAll("Int", GroupLaws[Int].monoid)

Used for example to test Validated's Monoid and Semigroup instances here.

That is definitely something which should be mentioned in the documentation about the laws (#1585).

[Daenyth]

For anyone watching / future me, checkAll comes from the Discipline test mixin