Add test to transform from M[A] to M[B]

Author: btlines

project/build.properties

@@ -1 +1 @@
-sbt.version=1.0.4
+sbt.version=1.0.4

src/main/scala/fluent/internal/Transformer.scala

@@ -109,6 +109,12 @@ trait ImplicitTransformersPriority3 extends ImplicitTransformersPriority2 {
     // There is no instance of CNil, so this won't be used
     Left(TransformError("Can't transform into CNil"))
   }
+
+  implicit def optionExtractorTransformer[A, B](implicit
+    transform: Transformer[A, B]
+  ): Transformer[Option[A], B] = instance { a: Option[A] =>
+    a.map(transform.apply) getOrElse Left(TransformError("Missing required field"))
+  }
 }
 
 trait ImplicitTransformersPriority4 extends ImplicitTransformersPriority3 {
@@ -192,12 +198,6 @@ trait ImplicitTransformersPriority4 extends ImplicitTransformersPriority3 {
 }
 
 trait ImplicitTransformersPriority5 extends ImplicitTransformersPriority4 {
-  implicit def optionExtractorTransformer[A, B](implicit
-    transform: Transformer[A, B]
-  ): Transformer[Option[A], B] = instance { a: Option[A] =>
-    a.map(transform.apply) getOrElse Left(TransformError("Missing required field"))
-  }
-
   implicit def extractorTransformer[A, B](implicit
     generic: Generic.Aux[A, B :: HNil]
   ): Transformer[A, B] = instance { a: A =>

src/test/scala/fluent/FluentSpec.scala

@@ -44,13 +44,18 @@ class FluentSpec extends WordSpecLike with Matchers {
       radius = 3.0,
       color = Some(Internal.Color.Red)
     )
-    "translate External.Circle transformTo Internal.Circle" in {
+    "tranform External.Circle into Internal.Circle" in {
       externalCircle.changeTo[Internal.Circle] shouldBe Right(internalCircle)
     }
-    "translate Internal.Circle transformTo External.Circle" in {
+    "transform Internal.Circle into External.Circle" in {
       internalCircle.changeTo[External.Circle] shouldBe Right(externalCircle)
     }
-
+    "transform Option[Internal.Circle] into Option[External.Circle]" in {
+      import cats.instances.either._
+      import cats.instances.option._
+      Option(internalCircle).changeTo[Option[External.Circle]] shouldBe Right(Some(externalCircle))
+      (None: Option[Internal.Circle]).changeTo[Option[External.Circle]] shouldBe Right(None)
+    }
     val externalPost = External.Post(
       author = "Misty",
       body = "#Fluent is a cool library to implement your #DDD #translationLayer seamlessly",