Merge pull request #1417 from travisbrown/topic/stack-unsafe-monad-tests

Add stackUnsafeMonad to MonadTests

build.sbt

@@ -264,7 +264,7 @@ lazy val laws = crossProject.crossType(CrossType.Pure)
   .settings(catsSettings:_*)
   .settings(disciplineDependencies:_*)
   .configureCross(disableScoverage210Jvm)
-  .settings(libraryDependencies ++= Seq("org.typelevel" %%% "catalysts-platform" % "0.0.4"))
+  .settings(testingDependencies: _*)
   .jsSettings(commonJsSettings:_*)
   .jvmSettings(commonJvmSettings:_*)
   .jsSettings(coverageEnabled := false)

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

@@ -37,6 +37,34 @@ trait MonadTests[F[_]] extends ApplicativeTests[F] with FlatMapTests[F] {
       ) ++ (if (Platform.isJvm) Seq[(String, Prop)]("tailRecM stack safety" -> laws.tailRecMStackSafety) else Seq.empty)
     }
   }
+
+  def stackUnsafeMonad[A: Arbitrary: Eq, B: Arbitrary: Eq, C: Arbitrary: Eq](implicit
+    ArbFA: Arbitrary[F[A]],
+    ArbFB: Arbitrary[F[B]],
+    ArbFC: Arbitrary[F[C]],
+    ArbFAtoB: Arbitrary[F[A => B]],
+    ArbFBtoC: Arbitrary[F[B => C]],
+    CogenA: Cogen[A],
+    CogenB: Cogen[B],
+    CogenC: Cogen[C],
+    EqFA: Eq[F[A]],
+    EqFB: Eq[F[B]],
+    EqFC: Eq[F[C]],
+    EqFABC: Eq[F[(A, B, C)]],
+    EqFInt: Eq[F[Int]],
+    iso: Isomorphisms[F]
+  ): RuleSet = {
+    new RuleSet {
+      def name: String = "monad (stack-unsafe)"
+      def bases: Seq[(String, RuleSet)] = Nil
+      def parents: Seq[RuleSet] = Seq(applicative[A, B, C], flatMap[A, B, C])
+      def props: Seq[(String, Prop)] = Seq(
+        "monad left identity" -> forAll(laws.monadLeftIdentity[A, B] _),
+        "monad right identity" -> forAll(laws.monadRightIdentity[A] _),
+        "map flatMap coherence" -> forAll(laws.mapFlatMapCoherence[A, B] _)
+      )
+    }
+  }
 }
 
 object MonadTests {

laws/src/test/scala/cats/laws/discipline/MonadTestsTests.scala

@@ -0,0 +1,15 @@
+package cats
+package laws
+package discipline
+
+import cats.instances.all._
+import cats.laws.discipline.arbitrary._
+import org.scalatest.FunSuite
+import org.typelevel.discipline.scalatest.Discipline
+
+class MonadTestsTests extends FunSuite with Discipline {
+  // We don't use `stackUnsafeMonad` in our laws checking for instances in Cats,
+  // so we confirm here that the laws pass for `Eval` (the monad instance for
+  // which is actually stack safe, like all other monad instances in Cats.)
+  checkAll("Eval[Int]", MonadTests[Eval].stackUnsafeMonad[Int, Int, Int])
+}