Port TraverseSuite to Scala 3

build.sbt

@@ -15,7 +15,7 @@ val catsVersion = "2.6.1"
 val disciplineMunitVersion = "1.0.9"
 val kindProjectorVersion = "0.13.0"
 val shapeless2Version = "2.3.7"
-val shapeless3Version = "3.0.2"
+val shapeless3Version = "3.0.3"
 
 lazy val commonSettings = Seq(
   scalacOptions := Seq(

core/src/test/scala-3/cats/derived/TraverseSuite.scala

@@ -0,0 +1,70 @@
+package cats.derived
+
+import cats.{Eq, Traverse}
+import cats.laws.discipline.{SerializableTests, TraverseTests}
+import org.scalacheck.Arbitrary
+
+import scala.compiletime.*
+
+class TraverseSuite extends KittensSuite:
+  import TestDefns.*
+  import TraverseSuite.*
+
+  inline def traverseTests[F[_]]: TraverseTests[F] =
+    TraverseTests[F](summonInline)
+
+  inline def testTraverse(inline context: String): Unit =
+    checkAll(s"$context.Traverse[IList]", traverseTests[IList].traverse[Int, Double, String, Long, Option, Option])
+    checkAll(s"$context.Traverse[Tree]", traverseTests[Tree].traverse[Int, Double, String, Long, Option, Option])
+    checkAll(
+      s"$context.Traverse[GenericAdt]",
+      traverseTests[GenericAdt].traverse[Int, Double, String, Long, Option, Option]
+    )
+    checkAll(s"$context.Traverse[OptList]", traverseTests[OptList].traverse[Int, Double, String, Long, Option, Option])
+    checkAll(
+      s"$context.Traverse[ListSnoc]",
+      traverseTests[ListSnoc].traverse[Int, Double, String, Long, Option, Option]
+    )
+    checkAll(s"$context.Traverse[AndChar]", traverseTests[AndChar].traverse[Int, Double, String, Long, Option, Option])
+    checkAll(
+      s"$context.Traverse[Interleaved]",
+      traverseTests[Interleaved].traverse[Int, Double, String, Long, Option, Option]
+    )
+    checkAll(s"$context.Traverse is Serializable", SerializableTests.serializable(summonInline[Traverse[Tree]]))
+
+  locally {
+    import auto.traverse.given
+    testTraverse("auto")
+  }
+
+  locally {
+    import semiInstances.given
+    testTraverse("semiauto")
+  }
+
+end TraverseSuite
+
+object TraverseSuite:
+  import TestDefns.*
+
+  type OptList[A] = Option[List[A]]
+  type ListSnoc[A] = List[Snoc[A]]
+
+  // FIXME: Doesn't work if we define `ListAndNel` as a type alias
+  case class AndChar[A](value: A, letter: Char)
+  object AndChar:
+    given [A: Eq]: Eq[AndChar[A]] =
+      Eq.by(ac => (ac.value, ac.letter))
+    given [A: Arbitrary]: Arbitrary[AndChar[A]] =
+      Arbitrary(Arbitrary.arbitrary[(A, Char)].map(apply[A].tupled))
+
+  object semiInstances:
+    given Traverse[IList] = semiauto.traverse
+    given Traverse[Tree] = semiauto.traverse
+    given Traverse[GenericAdt] = semiauto.traverse
+    given Traverse[OptList] = semiauto.traverse
+    given Traverse[ListSnoc] = semiauto.traverse
+    given Traverse[AndChar] = semiauto.traverse
+    given Traverse[Interleaved] = semiauto.traverse
+
+end TraverseSuite