Ensure all derived typeclasses are Serializable (#166)

We use our own `OrElse` which we anyway do now for Scala 2.13.
This unblocks us from waiting on a shapeless release for Serializable.

core/src/main/scala-2.11/cats/derived/util/versionspecific.scala

@@ -2,8 +2,28 @@ package cats.derived.util
 
 import scala.util.hashing.MurmurHash3
 
-private[derived] object VersionSpecific {
+object VersionSpecific {
   type Lazy[+A] = shapeless.Lazy[A]
-  type OrElse[+A, +B] = shapeless.OrElse[A, B]
-  def productSeed(x: Product): Int = MurmurHash3.productSeed
+  private[derived] def productSeed(x: Product): Int = MurmurHash3.productSeed
+
+  sealed trait OrElse[+A, +B] extends Serializable {
+    def fold[C](prim: A => C, sec: B => C): C
+    def unify[C >: A](implicit ev: B <:< C): C = fold(identity, ev)
+  }
+
+  final class Primary[+A](value: A) extends OrElse[A, Nothing] {
+    def fold[C](prim: A => C, sec: Nothing => C): C = prim(value)
+  }
+
+  final class Secondary[+B](value: => B) extends OrElse[Nothing, B] {
+    def fold[C](prim: Nothing => C, sec: B => C): C = sec(value)
+  }
+
+  object OrElse extends OrElse0 {
+    implicit def primary[A, B](implicit a: A): A OrElse B = new Primary(a)
+  }
+
+  private[util] abstract class OrElse0 {
+    implicit def secondary[A, B](implicit b: Lazy[B]): A OrElse B = new Secondary(b.value)
+  }
 }

core/src/main/scala-2.12/cats/derived/util/versionspecific.scala

@@ -2,8 +2,28 @@ package cats.derived.util
 
 import scala.util.hashing.MurmurHash3
 
-private[derived] object VersionSpecific {
+object VersionSpecific {
   type Lazy[+A] = shapeless.Lazy[A]
-  type OrElse[+A, +B] = shapeless.OrElse[A, B]
-  def productSeed(x: Product): Int = MurmurHash3.productSeed
+  private[derived] def productSeed(x: Product): Int = MurmurHash3.productSeed
+
+  sealed trait OrElse[+A, +B] extends Serializable {
+    def fold[C](prim: A => C, sec: B => C): C
+    def unify[C >: A](implicit ev: B <:< C): C = fold(identity, ev)
+  }
+
+  final class Primary[+A](value: A) extends OrElse[A, Nothing] {
+    def fold[C](prim: A => C, sec: Nothing => C): C = prim(value)
+  }
+
+  final class Secondary[+B](value: => B) extends OrElse[Nothing, B] {
+    def fold[C](prim: Nothing => C, sec: B => C): C = sec(value)
+  }
+
+  object OrElse extends OrElse0 {
+    implicit def primary[A, B](implicit a: A): A OrElse B = new Primary(a)
+  }
+
+  private[util] abstract class OrElse0 {
+    implicit def secondary[A, B](implicit b: Lazy[B]): A OrElse B = new Secondary(b.value)
+  }
 }

core/src/main/scala-2.13/cats/derived/util/versionspecific.scala

@@ -2,20 +2,20 @@ package cats.derived.util
 
 import scala.util.hashing.MurmurHash3
 
-private[derived] object VersionSpecific {
+object VersionSpecific {
 
-  def productSeed(x: Product): Int =
+  private[derived] def productSeed(x: Product): Int =
     MurmurHash3.mix(MurmurHash3.productSeed, x.productPrefix.hashCode)
 
-  abstract class Lazy[+A] {
+  abstract class Lazy[+A] extends Serializable {
     def value(): A
   }
 
   object Lazy {
     implicit def instance[A](implicit ev: => A): Lazy[A] = () => ev
   }
 
-  sealed trait OrElse[+A, +B] {
+  sealed trait OrElse[+A, +B] extends Serializable {
     def fold[C](prim: A => C, sec: B => C): C
     def unify[C >: A](implicit ev: B <:< C): C = fold(identity, ev)
   }

core/src/main/scala/cats/derived/hash.scala

@@ -11,7 +11,7 @@ object MkHash extends MkHashDerivation {
   def apply[A](implicit ev: MkHash[A]): MkHash[A] = ev
 }
 
-private[derived] trait HashBuilder[A] {
+private[derived] trait HashBuilder[A] extends Serializable {
   def hashes(x: A): List[Int]
   def eqv(x: A, y: A): Boolean
 

core/src/main/scala/cats/derived/util/liftSome.scala

@@ -21,7 +21,7 @@ import shapeless._
 /** Summons all available instances of the typeclass `F` for members of the coproduct `C`.
   * Unlike `LiftAll` members of the coproduct without an instance will be skipped in the result.
   */
-sealed trait LiftSome[F[_], C <: Coproduct] {
+sealed trait LiftSome[F[_], C <: Coproduct] extends Serializable {
   type Out <: HList
   def instances: Out
 }

core/src/test/scala/cats/derived/KittensSuite.scala

@@ -20,36 +20,10 @@ import cats.syntax.AllSyntax
 import org.scalatest.funsuite.AnyFunSuite
 import org.typelevel.discipline.scalatest.Discipline
 
-import scala.util.control.NonFatal
-
 /**
  * An opinionated stack of traits to improve consistency and reduce
  * boilerplate in Kittens tests. Note that unlike the corresponding
  * CatsSuite in the Cat project, this trait does not mix in any
  * instances.
  */
-trait KittensSuite extends AnyFunSuite with Discipline with AllSyntax with SerializableTest
-
-
-trait SerializableTest {
-  def isSerializable[T](a: T): Boolean = {
-  import java.io.{ ByteArrayInputStream, ByteArrayOutputStream, ObjectInputStream, ObjectOutputStream }
-    val baos = new ByteArrayOutputStream()
-    val oos = new ObjectOutputStream(baos)
-    var ois: ObjectInputStream = null
-    try {
-      oos.writeObject(a)
-      oos.close()
-      val bais = new ByteArrayInputStream(baos.toByteArray())
-      ois = new ObjectInputStream(bais)
-      val a2 = ois.readObject()
-      ois.close()
-      true
-    } catch { case NonFatal(t) =>
-      throw new Exception(t)
-    } finally {
-      oos.close()
-      if (ois != null) ois.close()
-    }
-  }
-}
+trait KittensSuite extends AnyFunSuite with Discipline with AllSyntax

core/src/test/scala/cats/derived/applicative.scala

@@ -18,7 +18,7 @@ package cats
 package derived
 
 import cats.instances.all._
-import cats.laws.discipline.ApplicativeTests
+import cats.laws.discipline.{ApplicativeTests, SerializableTests}
 import cats.laws.discipline.SemigroupalTests.Isomorphisms
 
 class ApplicativeSuite extends KittensSuite {
@@ -44,6 +44,7 @@ class ApplicativeSuite extends KittensSuite {
     checkAll(s"$context.Applicative[AndInt]", ApplicativeTests[AndInt].applicative[Int, String, Long])
     checkAll(s"$context.Applicative[Interleaved]", ApplicativeTests[Interleaved].applicative[Int, String, Long])
     checkAll(s"$context.Applicative[ListBox]", ApplicativeTests[ListBox].applicative[Int, String, Long])
+    checkAll(s"$context.Applicative is Serializable", SerializableTests.serializable(Applicative[Interleaved]))
   }
 
   {

core/src/test/scala/cats/derived/apply.scala

@@ -18,7 +18,7 @@ package cats
 package derived
 
 import cats.instances.all._
-import cats.laws.discipline.ApplyTests
+import cats.laws.discipline.{ApplyTests, SerializableTests}
 import cats.laws.discipline.SemigroupalTests.Isomorphisms
 
 class ApplySuite extends KittensSuite {
@@ -44,6 +44,7 @@ class ApplySuite extends KittensSuite {
     checkAll(s"$context.Apply[AndInt]", ApplyTests[AndInt].apply[Int, String, Long])
     checkAll(s"$context.Apply[Interleaved]", ApplyTests[Interleaved].apply[Int, String, Long])
     checkAll(s"$context.Apply[ListBox]", ApplyTests[ListBox].apply[Int, String, Long])
+    checkAll(s"$context.Apply is Serializable", SerializableTests.serializable(Apply[Interleaved]))
   }
 
   {

core/src/test/scala/cats/derived/consk.scala

@@ -17,6 +17,7 @@
 package cats.derived
 
 import alleycats.ConsK
+import cats.laws.discipline.SerializableTests
 import org.scalatest.prop.{Generator, GeneratorDrivenPropertyChecks}
 
 class ConsKSuite extends KittensSuite with GeneratorDrivenPropertyChecks {
@@ -28,7 +29,7 @@ class ConsKSuite extends KittensSuite with GeneratorDrivenPropertyChecks {
   def testConsK(context: String)(implicit iList: ConsK[IList], snoc: ConsK[Snoc]): Unit = {
     test(s"$context.ConsK[IList]")(checkConsK[IList, Int](INil())(IList.fromSeq))
     test(s"$context.ConsK[Snoc]")(checkConsK[Snoc, Int](SNil())(xs => Snoc.fromSeq(xs.reverse)))
-    test(s"$context.ConsK is Serializable")(assert(isSerializable(iList)))
+    checkAll(s"$context.ConsK is Serializable", SerializableTests.serializable(ConsK[IList]))
   }
 
   {

core/src/test/scala/cats/derived/empty.scala

@@ -19,6 +19,7 @@ package derived
 
 import alleycats.Empty
 import cats.instances.all._
+import cats.laws.discipline.SerializableTests
 import shapeless.test.illTyped
 
 class EmptySuite extends KittensSuite {
@@ -47,6 +48,7 @@ class EmptySuite extends KittensSuite {
     test(s"$context.Empty respects existing instances")(assert(box.empty == Box(Mask(0xffffffff))))
     // Known limitation of recursive typeclass derivation.
     test(s"$context.Empty[Chain] throws a StackOverflowError")(assertThrows[StackOverflowError](chain.empty))
+    checkAll(s"$context.Empty is Serializable", SerializableTests.serializable(Empty[Interleaved[String]]))
   }
 
   {

core/src/test/scala/cats/derived/emptyk.scala

@@ -19,6 +19,7 @@ package cats.derived
 import alleycats.{EmptyK, Pure}
 import alleycats.std.all._
 import cats.data.NonEmptyList
+import cats.laws.discipline.SerializableTests
 import cats.instances.all._
 import shapeless.test.illTyped
 
@@ -43,6 +44,7 @@ class EmptyKSuite extends KittensSuite {
     test(s"$context.EmptyK[CaseClassWOption]")(assert(caseClassWOption.empty == CaseClassWOption(None)))
     test(s"$context.EmptyK[NelOption]")(assert(nelOption.empty == NonEmptyList.of(None)))
     test(s"$context.EmptyK respects existing instances")(assert(boxColor.empty == Box(Color(255, 255, 255))))
+    checkAll(s"$context.EmptyK is Serializable", SerializableTests.serializable(EmptyK[PList]))
   }
 
   implicit val pureBox: Pure[Box] = new Pure[Box] {

core/src/test/scala/cats/derived/eq.scala

@@ -17,7 +17,7 @@
 package cats
 package derived
 
-import cats.kernel.laws.discipline._
+import cats.kernel.laws.discipline.{EqTests, SerializableTests}
 import cats.instances.all._
 
 class EqSuite extends KittensSuite {
@@ -39,6 +39,7 @@ class EqSuite extends KittensSuite {
     checkAll(s"$context.Eq[Interleaved[Int]]", EqTests[Interleaved[Int]].eqv)
     checkAll(s"$context.Eq[Tree[Int]]", EqTests[Tree[Int]].eqv)
     checkAll(s"$context.Eq[Recursive]", EqTests[Recursive].eqv)
+    checkAll(s"$context.Eq is Serializable", SerializableTests.serializable(Eq[Tree[Int]]))
   }
 
   {

core/src/test/scala/cats/derived/foldable.scala

@@ -18,7 +18,7 @@ package cats
 package derived
 
 import cats.instances.all._
-import cats.laws.discipline.FoldableTests
+import cats.laws.discipline.{FoldableTests, SerializableTests}
 import org.scalacheck.Arbitrary
 
 class FoldableSuite extends KittensSuite {
@@ -49,6 +49,7 @@ class FoldableSuite extends KittensSuite {
     checkAll(s"$context.Foldable[AndChar]", FoldableTests[AndChar].foldable[Int, Long])
     checkAll(s"$context.Foldable[Interleaved]", FoldableTests[Interleaved].foldable[Int, Long])
     checkAll(s"$context.Foldable[BoxNel]]", FoldableTests[BoxNel].foldable[Int, Long])
+    checkAll(s"$context.Foldable is Serializable", SerializableTests.serializable(Foldable[Tree]))
 
     val n = 10000
     val largeIList = IList.fromSeq(1 until n)

core/src/test/scala/cats/derived/functor.scala

@@ -18,7 +18,7 @@ package cats
 package derived
 
 import cats.instances.all._
-import cats.laws.discipline.FunctorTests
+import cats.laws.discipline.{FunctorTests, SerializableTests}
 
 class FunctorSuite extends KittensSuite {
   import TestDefns._
@@ -44,6 +44,7 @@ class FunctorSuite extends KittensSuite {
     checkAll(s"$context.Functor[ListSnoc]", FunctorTests[ListSnoc].functor[Int, String, Long])
     checkAll(s"$context.Functor[AndChar]", FunctorTests[AndChar].functor[Int, String, Long])
     checkAll(s"$context.Functor[Interleaved]", FunctorTests[Interleaved].functor[Int, String, Long])
+    checkAll(s"$context.Functor is Serializable", SerializableTests.serializable(Functor[Tree]))
 
     test(s"$context.Functor.map is stack safe") {
       val n = 10000

core/src/test/scala/cats/derived/hash.scala

@@ -1,7 +1,7 @@
 package cats
 package derived
 
-import cats.kernel.laws.discipline.HashTests
+import cats.kernel.laws.discipline.{HashTests, SerializableTests}
 import cats.instances.all._
 
 class HashSuite extends KittensSuite {
@@ -22,6 +22,7 @@ class HashSuite extends KittensSuite {
     // checkAll(s"$context.Hash[Interleaved[Int]]", HashTests[Interleaved[Int]].hash)
     checkAll(s"$context.Hash[Tree[Int]]", HashTests[Tree[Int]].hash)
     checkAll(s"$context.Hash[Recursive]", HashTests[Recursive].hash)
+    checkAll(s"$context.Hash is Serializable", SerializableTests.serializable(Hash[Tree[Int]]))
   }
 
   {

core/src/test/scala/cats/derived/monoid.scala

@@ -18,7 +18,7 @@ package cats.derived
 
 import cats.{Eq, Monoid}
 import cats.instances.all._
-import cats.kernel.laws.discipline._
+import cats.kernel.laws.discipline.{MonoidTests, SerializableTests}
 import org.scalacheck.Arbitrary
 
 class MonoidSuite extends KittensSuite {
@@ -36,6 +36,7 @@ class MonoidSuite extends KittensSuite {
     checkAll(s"$context.Monoid[Recursive]", MonoidTests[Recursive].monoid)
     checkAll(s"$context.Monoid[Interleaved[Int]]", MonoidTests[Interleaved[Int]].monoid)
     checkAll(s"$context.Monoid[Box[Mul]]", MonoidTests[Box[Mul]].monoid)
+    checkAll(s"$context.Monoid is Serializable", SerializableTests.serializable(Monoid[Interleaved[Int]]))
 
     test(s"$context.Monoid respects existing instances") {
       assert(box.empty == Box(Mul(1)))

core/src/test/scala/cats/derived/monoidk.scala

@@ -18,7 +18,7 @@ package cats
 package derived
 
 import cats.instances.all._
-import cats.laws.discipline.MonoidKTests
+import cats.laws.discipline.{MonoidKTests, SerializableTests}
 import org.scalacheck.Arbitrary
 
 class MonoidKSuite extends KittensSuite {
@@ -36,6 +36,7 @@ class MonoidKSuite extends KittensSuite {
     checkAll(s"$context.MonoidK[ComplexProduct]", MonoidKTests[ComplexProduct].monoidK[Char])
     checkAll(s"$context.MonoidK[CaseClassWOption]", MonoidKTests[CaseClassWOption].monoidK[Char])
     checkAll(s"$context.MonoidK[BoxMul]", MonoidKTests[BoxMul].monoidK[Char])
+    checkAll(s"$context.MonoidK is Serializable", SerializableTests.serializable(MonoidK[ComplexProduct]))
 
     test(s"$context.MonoidK respects existing instances") {
       assert(boxMul.empty[Char] == Box(Mul[Char](1)))

core/src/test/scala/cats/derived/order.scala

@@ -17,7 +17,7 @@
 package cats
 package derived
 
-import cats.kernel.laws.discipline._
+import cats.kernel.laws.discipline.{OrderTests, SerializableTests}
 import cats.instances.all._
 
 class OrderSuite extends KittensSuite {
@@ -35,6 +35,7 @@ class OrderSuite extends KittensSuite {
     checkAll(s"$context.Order[Interleaved[Int]]", OrderTests[Interleaved[Int]].order)
     checkAll(s"$context.Order[Recursive]", OrderTests[Recursive].order)
     checkAll(s"$context.Order[GenericAdt[Int]]", OrderTests[GenericAdt[Int]].order)
+    checkAll(s"$context.Order is Serializable", SerializableTests.serializable(Order[Interleaved[Int]]))
   }
 
   {

core/src/test/scala/cats/derived/partialOrder.scala

@@ -18,7 +18,7 @@ package cats
 package derived
 
 import cats.instances.all._
-import cats.kernel.laws.discipline._
+import cats.kernel.laws.discipline.{PartialOrderTests, SerializableTests}
 import org.scalacheck.{Arbitrary, Cogen}
 
 class PartialOrderSuite extends KittensSuite {
@@ -41,6 +41,7 @@ class PartialOrderSuite extends KittensSuite {
     checkAll(s"$context.PartialOrder[Tree[Int]]", PartialOrderTests[Tree[Int]].partialOrder)
     checkAll(s"$context.PartialOrder[Recursive]", PartialOrderTests[Recursive].partialOrder)
     checkAll(s"$context.PartialOrder[Box[KeyValue]]", PartialOrderTests[Box[KeyValue]].partialOrder)
+    checkAll(s"$context.PartialOrder is Serialiable", SerializableTests.serializable(PartialOrder[Tree[Int]]))
 
     test(s"$context.PartialOrder respects existing instances") {
       val x = Box(KeyValue("red", 1))

core/src/test/scala/cats/derived/pure.scala

@@ -18,8 +18,9 @@ package cats
 package derived
 
 import alleycats.Pure
-import cats.instances.all._
 import cats.data.NonEmptyList
+import cats.instances.all._
+import cats.laws.discipline.SerializableTests
 import shapeless.test.illTyped
 
 class PureSuite extends KittensSuite {
@@ -45,6 +46,7 @@ class PureSuite extends KittensSuite {
     test(s"$context.Pure[NelOption]")(assert(nelOption.pure(42) == NonEmptyList.of(Some(42))))
     test(s"$context.Pure[Interleaved]")(assert(interleaved.pure('x') == Interleaved(0, 'x', 0, 'x' :: Nil, "")))
     test(s"$context.Pure respects existing instances")(assert(boxColor.pure(()) == Box(Color(255, 255, 255))))
+    checkAll(s"$context.Pure is Serializable", SerializableTests.serializable(Pure[Interleaved]))
   }
 
   {

core/src/test/scala/cats/derived/semigroup.scala

@@ -18,7 +18,7 @@ package cats
 package derived
 
 import cats.instances.all._
-import cats.kernel.laws.discipline._
+import cats.kernel.laws.discipline.{SemigroupTests, SerializableTests}
 import org.scalacheck.Arbitrary
 
 class SemigroupSuite extends KittensSuite {
@@ -36,6 +36,7 @@ class SemigroupSuite extends KittensSuite {
     checkAll(s"$context.Semigroup[Recursive]", SemigroupTests[Recursive].semigroup)
     checkAll(s"$context.Semigroup[Interleaved[Int]]", SemigroupTests[Interleaved[Int]].semigroup)
     checkAll(s"$context.Semigroup[Box[Mul]]", SemigroupTests[Box[Mul]].semigroup)
+    checkAll(s"$context.Semigroup is Serializable", SerializableTests.serializable(Semigroup[Interleaved[Int]]))
 
     test(s"$context.Semigroup respects existing instances") {
       assert(box.combine(Box(Mul(5)), Box(Mul(5))).content.value == 25)