Merge pull request #748 from ceedubs/kleisli-identities

Add tests of kleisli left and right identity laws

Author: stew

tests/src/test/scala/cats/tests/OptionTests.scala

@@ -1,7 +1,7 @@
 package cats
 package tests
 
-import cats.laws.{ApplicativeLaws, CoflatMapLaws, FlatMapLaws}
+import cats.laws.{ApplicativeLaws, CoflatMapLaws, FlatMapLaws, MonadLaws}
 import cats.laws.discipline.{TraverseTests, CoflatMapTests, MonadCombineTests, SerializableTests, MonoidalTests}
 import cats.laws.discipline.eq._
 
@@ -60,4 +60,20 @@ class OptionTests extends CatsSuite {
       isEq.lhs should === (isEq.rhs)
     }
   }
+
+  val monadLaws = MonadLaws[Option]
+
+  test("Kleisli left identity") {
+    forAll { (a: Int, f: Int => Option[Long]) =>
+      val isEq = monadLaws.kleisliLeftIdentity(a, f)
+      isEq.lhs should === (isEq.rhs)
+    }
+  }
+
+  test("Kleisli right identity") {
+    forAll { (a: Int, f: Int => Option[Long]) =>
+      val isEq = monadLaws.kleisliRightIdentity(a, f)
+      isEq.lhs should === (isEq.rhs)
+    }
+  }
 }