make stack-safety-test for tailRecM in MonadTests only fail when chec…

…king the test

Previously, already calling 'MonadTests[Signal].monad[Int, Int, Int].all' would cause a StackOverflowError, now this is only caused when executing the test and can be captured e.g. by using check.

In our case, this solved a ScalaTest test suite from aborting and thus not executing any tests to just a failing test.

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

@@ -34,7 +34,7 @@ trait MonadTests[F[_]] extends ApplicativeTests[F] with FlatMapTests[F] {
         "monad left identity" -> forAll(laws.monadLeftIdentity[A, B] _),
         "monad right identity" -> forAll(laws.monadRightIdentity[A] _),
         "map flatMap coherence" -> forAll(laws.mapFlatMapCoherence[A, B] _)
-      ) ++ (if (Platform.isJvm) Seq[(String, Prop)]("tailRecM stack safety" -> laws.tailRecMStackSafety) else Seq.empty)
+      ) ++ (if (Platform.isJvm) Seq[(String, Prop)]("tailRecM stack safety" -> Prop.lzy(laws.tailRecMStackSafety)) else Seq.empty)
     }
   }