NonEmptyList comonad is not commutative

core/src/main/scala/cats/data/NonEmptyList.scala

@@ -367,8 +367,8 @@ object NonEmptyList extends NonEmptyListInstances {
 private[data] sealed trait NonEmptyListInstances extends NonEmptyListInstances0 {
 
   implicit val catsDataInstancesForNonEmptyList: SemigroupK[NonEmptyList] with Reducible[NonEmptyList]
-      with CommutativeComonad[NonEmptyList] with NonEmptyTraverse[NonEmptyList] with Monad[NonEmptyList] =
-    new NonEmptyReducible[NonEmptyList, List] with SemigroupK[NonEmptyList] with CommutativeComonad[NonEmptyList]
+      with Comonad[NonEmptyList] with NonEmptyTraverse[NonEmptyList] with Monad[NonEmptyList] =
+    new NonEmptyReducible[NonEmptyList, List] with SemigroupK[NonEmptyList] with Comonad[NonEmptyList]
       with Monad[NonEmptyList] with NonEmptyTraverse[NonEmptyList] {
 
       def combineK[A](a: NonEmptyList[A], b: NonEmptyList[A]): NonEmptyList[A] =

laws/src/main/scala/cats/laws/ArrowLaws.scala

@@ -34,6 +34,9 @@ trait ArrowLaws[F[_, _]] extends CategoryLaws[F] with StrongLaws[F] {
   def arrowAssociation[A, B, C, D](f: F[A, B]): IsEq[F[((A, C), D), (B, (C, D))]] =
     (f.first[C].first[D] andThen F.lift(assoc[B, C, D])) <-> (F.lift(assoc[A, C, D]) andThen f.first[(C, D)])
 
+  def splitConsistentWithAndThen[A, B, C, D](f: F[A, B], g: F[C, D]): IsEq[F[(A, C), (B, D)]] =
+    F.split(f, g) <-> (f.first andThen g.second)
+
   private def fst[A, B](p: (A, B)): A = p._1
 
   private def assoc[A, B, C](p: ((A, B), C)): (A, (B, C)) = (p._1._1, (p._1._2, p._2))

laws/src/main/scala/cats/laws/discipline/Arbitrary.scala

@@ -76,8 +76,6 @@ object arbitrary extends ArbitraryInstances0 {
       B.perturb(seed, _),
       (a, b) => A.perturb(B.perturb(seed, b), a)))
 
-  implicit def catsLawsArbitraryForCokleisli[F[_], A, B](implicit AFA: Arbitrary[F[A]], CFA: Cogen[F[A]], B: Arbitrary[B]): Arbitrary[Cokleisli[F, A, B]] =
-    Arbitrary(Arbitrary.arbitrary[F[A] => B].map(Cokleisli(_)))
 
   implicit def catsLawsArbitraryForOptionT[F[_], A](implicit F: Arbitrary[F[Option[A]]]): Arbitrary[OptionT[F, A]] =
     Arbitrary(F.arbitrary.map(OptionT.apply))
@@ -161,6 +159,9 @@ object arbitrary extends ArbitraryInstances0 {
   implicit def catsLawArbitraryForReader[A: Arbitrary: Cogen, B: Arbitrary]: Arbitrary[Reader[A, B]] =
     catsLawsArbitraryForKleisli[Id, A, B]
 
+  implicit def catsLawArbitraryForCokleisliId[A: Arbitrary: Cogen, B: Arbitrary]: Arbitrary[Cokleisli[Id, A, B]] =
+    catsLawsArbitraryForCokleisli[Id, A, B]
+
   implicit def catsLawsAribtraryForReaderWriterStateT[F[_]: Applicative, E, S, L, A](implicit F: Arbitrary[(E, S) => F[(L, S, A)]]): Arbitrary[ReaderWriterStateT[F, E, S, L, A]] =
     Arbitrary(F.arbitrary.map(ReaderWriterStateT(_)))
 }
@@ -179,4 +180,6 @@ private[discipline] sealed trait ArbitraryInstances0 {
   implicit def catsLawsArbitraryForKleisli[F[_], A, B](implicit AA: Arbitrary[A], CA: Cogen[A], F: Arbitrary[F[B]]): Arbitrary[Kleisli[F, A, B]] =
     Arbitrary(Arbitrary.arbitrary[A => F[B]].map(Kleisli(_)))
 
+  implicit def catsLawsArbitraryForCokleisli[F[_], A, B](implicit AFA: Arbitrary[F[A]], CFA: Cogen[F[A]], B: Arbitrary[B]): Arbitrary[Cokleisli[F, A, B]] =
+    Arbitrary(Arbitrary.arbitrary[F[A] => B].map(Cokleisli(_)))
 }

laws/src/main/scala/cats/laws/discipline/ArrowTests.scala

@@ -48,7 +48,8 @@ trait ArrowTests[F[_, _]] extends CategoryTests[F] with StrongTests[F] {
         "arrow functor" -> forAll(laws.arrowFunctor[A, B, C, D] _),
         "arrow exchange" -> forAll(laws.arrowExchange[A, B, C, D] _),
         "arrow unit" -> forAll(laws.arrowUnit[A, B, C] _),
-        "arrow association" -> forAll(laws.arrowAssociation[A, B, C, D] _)
+        "arrow association" -> forAll(laws.arrowAssociation[A, B, C, D] _),
+        "split consistent with andThen" -> forAll(laws.splitConsistentWithAndThen[A, B, C, D] _)
       )
     }
 }

tests/src/test/scala/cats/tests/CokleisliTests.scala

@@ -36,11 +36,17 @@ class CokleisliTests extends SlowCatsSuite {
   checkAll("Cokleisli[Option, Int, Int]", ContravariantTests[Cokleisli[Option, ?, Int]].contravariant[Int, Int, Int])
   checkAll("Contravariant[Cokleisli[Option, ?, Int]]", SerializableTests.serializable(Contravariant[Cokleisli[Option, ?, Int]]))
 
-  checkAll("Cokleisli[NonEmptyList, Int, Int]", CommutativeArrowTests[Cokleisli[NonEmptyList, ?, ?]].commutativeArrow[Int, Int, Int, Int, Int, Int])
-  checkAll("Arrow[Cokleisli[NonEmptyList, ?, ?]]", SerializableTests.serializable(CommutativeArrow[Cokleisli[NonEmptyList, ?, ?]]))
 
   checkAll("Cokleisli[NonEmptyList, Int, Int]", MonoidKTests[λ[α => Cokleisli[NonEmptyList, α, α]]].monoidK[Int])
   checkAll("MonoidK[λ[α => Cokleisli[NonEmptyList, α, α]]]", SerializableTests.serializable(MonoidK[λ[α => Cokleisli[NonEmptyList, α, α]]]))
+  {
+    implicit def cokleisliIdEq[A, B](implicit A: Arbitrary[A], FB: Eq[B]): Eq[Cokleisli[Id, A, B]] =
+      Eq.by[Cokleisli[Id, A, B], A => B](_.run)
+
+    checkAll("Cokleisli[Id, Int, Int]", CommutativeArrowTests[Cokleisli[Id, ?, ?]].commutativeArrow[Int, Int, Int, Int, Int, Int])
+    checkAll("CommutativeArrow[Cokleisli[Id, ?, ?]]", SerializableTests.serializable(CommutativeArrow[Cokleisli[Id, ?, ?]]))
+  }
+
 
   checkAll("Cokleisli[List, Int, Int]", SemigroupKTests[λ[α => Cokleisli[List, α, α]]].semigroupK[Int])
   checkAll("SemigroupK[λ[α => Cokleisli[List, α, α]]]", SerializableTests.serializable(SemigroupK[λ[α => Cokleisli[List, α, α]]]))

tests/src/test/scala/cats/tests/NonEmptyListTests.scala

@@ -4,7 +4,7 @@ package tests
 import cats.kernel.laws.{GroupLaws, OrderLaws}
 
 import cats.data.NonEmptyList
-import cats.laws.discipline.{CommutativeComonadTests, SemigroupKTests, MonadTests, SerializableTests, NonEmptyTraverseTests, ReducibleTests }
+import cats.laws.discipline.{ComonadTests, SemigroupKTests, MonadTests, SerializableTests, NonEmptyTraverseTests, ReducibleTests }
 import cats.laws.discipline.arbitrary._
 
 class NonEmptyListTests extends CatsSuite {
@@ -29,8 +29,8 @@ class NonEmptyListTests extends CatsSuite {
   checkAll("NonEmptyList[Int]", GroupLaws[NonEmptyList[Int]].semigroup)
   checkAll("Semigroup[NonEmptyList[Int]]", SerializableTests.serializable(Semigroup[NonEmptyList[Int]]))
 
-  checkAll("NonEmptyList[Int]", CommutativeComonadTests[NonEmptyList].commutativeComonad[Int, Int, Int])
-  checkAll("CommutativeComonad[NonEmptyList]", SerializableTests.serializable(CommutativeComonad[NonEmptyList]))
+  checkAll("NonEmptyList[Int]", ComonadTests[NonEmptyList].comonad[Int, Int, Int])
+  checkAll("Comonad[NonEmptyList]", SerializableTests.serializable(Comonad[NonEmptyList]))
 
   checkAll("NonEmptyList[ListWrapper[Int]]", OrderLaws[NonEmptyList[ListWrapper[Int]]].eqv)
   checkAll("Eq[NonEmptyList[ListWrapper[Int]]]", SerializableTests.serializable(Eq[NonEmptyList[ListWrapper[Int]]]))