Add scalafix for contramap (#1937)

* Add scalafix for contramap

* Remove redundancies

* Try to build scalafix with travis

* Working travis tests

* Publish snapshot before running scalafix

* Simplify denotation lookup

.travis.yml

@@ -4,7 +4,7 @@ sudo: required
 
 dist: trusty
 
-group: edge 
+group: edge
 
 git:
   depth: 9999

scalafix/build.sbt

@@ -16,8 +16,8 @@ lazy val input = project.settings(
 
 lazy val output = project.settings(
   libraryDependencies ++= Seq(
-    "org.typelevel" %% "cats-core" % "1.0.0-MF",
-    "org.typelevel" %% "cats-free" % "1.0.0-MF"
+    "org.typelevel" %% "cats-core" % "1.0.0-SNAPSHOT",
+    "org.typelevel" %% "cats-free" % "1.0.0-SNAPSHOT"
   ),
   scalacOptions += "-language:higherKinds"
 )

scalafix/input/src/main/scala/fix/v1_0_0/ContraMapToLMap.scala

@@ -0,0 +1,31 @@
+/*
+rule = "scala:fix.v1_0_0.ContraMapToLMap"
+ */
+package fix
+package to1_0_0
+
+
+
+object ContraMapToLMapTests {
+  import cats.Show
+  import cats.syntax.all._
+  import cats.instances.all._
+
+  val f: Int => String = _.toString
+
+  val g: Int => String = f.contramap(_ + 1)
+
+  object Foo
+  object Bar
+  object Baz
+
+  implicit val showFoo: Show[Foo.type] = Show.fromToString
+
+  val showBar: Show[Bar.type] = showFoo.contramap(_ => Foo)
+
+  val showBaz: Show[Baz.type] = Show[Foo.type].contramap(_ => Foo)
+
+  def getShowBar(): Show[Bar.type] = showBar
+
+  getShowBar().contramap((_: Int) => Bar)
+}

scalafix/output/src/main/scala/fix/v1_0_0/ContraMapToLMap.scala

@@ -0,0 +1,28 @@
+package fix
+package to1_0_0
+
+
+
+object ContraMapToLMapTests {
+  import cats.Show
+  import cats.syntax.all._
+  import cats.instances.all._
+
+  val f: Int => String = _.toString
+
+  val g: Int => String = f.lmap(_ + 1)
+
+  object Foo
+  object Bar
+  object Baz
+
+  implicit val showFoo: Show[Foo.type] = Show.fromToString
+
+  val showBar: Show[Bar.type] = showFoo.contramap(_ => Foo)
+
+  val showBaz: Show[Baz.type] = Show[Foo.type].contramap(_ => Foo)
+
+  def getShowBar(): Show[Bar.type] = showBar
+
+  getShowBar().contramap((_: Int) => Bar)
+}

scalafix/rules/src/main/scala/fix/Cats_v1_0_0.scala

@@ -2,6 +2,7 @@ package fix
 package v1_0_0
 
 import scalafix._
+import scalafix.syntax._
 import scalafix.util.SymbolMatcher
 import scala.meta._
 import scala.meta.contrib._
@@ -73,6 +74,23 @@ case class RemoveCartesianBuilder(index: SemanticdbIndex)
   }
 }
 
+// ref: https://github.com/typelevel/cats/issues/1850
+case class ContraMapToLMap(index: SemanticdbIndex)
+  extends SemanticRule(index, "UseLMapInsteadOfContraMap") {
+
+  override def fix(ctx: RuleCtx): Patch = {
+
+    val contraMatcher = SymbolMatcher.normalized(Symbol("_root_.cats.functor.Contravariant.Ops.`contramap`."))
+
+    val unApplyName = "catsUnapply2left"
+
+    ctx.tree.collect {
+      case Term.Apply(Term.Select(f, contraMatcher(contramap)), _) if f.denotation.exists(_.name == unApplyName) =>
+        ctx.replaceTree(contramap, "lmap")
+    }.asPatch
+  }
+}
+
 // ref: https://github.com/typelevel/cats/pull/1583
 case class RemoveUnapply(index: SemanticdbIndex)
     extends SemanticRule(index, "RemoveUnapply") {

scripts/travis-publish.sh

@@ -7,8 +7,9 @@
 #   b. Builds and tests for the JVM using the validateJVM target, and then
 #   c. Produces the coverage report, and then
 #   d. Clean is run (as part of coverageReport), to clear down the built artifacts
-# 2. The scala js build is executed, compiling the application and testing it for scala js.
-# 3. The validateJVM target is executed again, due to the fact that producing coverage with the
+# 2. The scalafix subdirectory is run, executing the tests inside.
+# 3. The scala js build is executed, compiling the application and testing it for scala js.
+# 4. The validateJVM target is executed again, due to the fact that producing coverage with the
 #    code coverage tool causes the byte code to be instrumented/modified to record the coverage
 #    metrics when the tests are executing. This causes the full JVM build to be run a second time.
 
@@ -34,6 +35,11 @@ free_js="$sbt_cmd validateFreeJS"
 js="$core_js && $free_js && $kernel_js"
 jvm="$sbt_cmd coverage validateJVM coverageReport && codecov"
 
+sbt ;coreJVM/publishLocal;freeJVM/publishLocal
+cd scalafix
+sbt tests/test
+cd ..
+
 if [[ $JS_BUILD == "true" ]]; then
 run_cmd="$js"
 else