Abstract over Specs2 test result kind to enable more consistent support for ScalaCheck#616
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djspiewak merged 2 commits intotypelevel:series/1.xfrom Jul 9, 2025
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…ind of test results This lets `CatsResource#withResource` accept test implementations that return kinds like `*` (`A`), `* -> *` (`F[A]`), and `(* -> *) -> *` (`org.scalacheck.effect.PropF[F]`).
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This PR introduces
AsFutureResult[A], which can be thought of an extension ofUnsafeRun[F].unsafeToFuture[A]when anAsResult[A]is available. As far as I can tell, this is necessary to support structures likeorg.scalacheck.effect.PropF[F], where it is not possible to write an instance ofUnsafeRun[PropF], sincePropF#checkreturnsResultand notA. (This doesn't work, even using e.g.UnsafeRun[({ type λ[α] = PropF[F] })#λ].)This lets us abstract over different kinds of results, such as
A(assuming anAsResult[A]),F[A](assuming anUnsafeRun[F]andAsResult[A]), orPropF[F](assuming anUnsafeRun[F]).If this is merged, I'll make a followup PR to typelevel/scalacheck-effect adding a new
scalacheck-effect-specs2project with atrait Specs2ScalaCheckEffectwhich will provide an instance ofAsFutureResult[PropF[F]].This enables users to use
CatsResource#withResourcewith many different kinds of tests. This was motivated by work I recently completed introducing Cats Effect into parts of an existing project. That project had existing tests that returnedMatchResult[A]andMatchResult[scala.concurrent.Future[A]](as well as some tests implemented in Twitter'sFuture). With these changes, I was able to add tests that operate inIOandPropFwhile minimizing the changes needed to the existing tests. (Without these tests, using the existing tests withwithResourceswould have involved a fair amount of boilerplate wrapping the existing tests inIO.)