Fixes etsy#16: Make sbt-checkstyle-plugin an AutoPlugin

Author: ajsquared

README.md

@@ -17,12 +17,12 @@ Add the following lines to `project/plugins.sbt`:
 addSbtPlugin("com.etsy" % "sbt-checkstyle-plugin" % "1.0.0")
 ```
 
-Then add the following lines to `build.sbt`:
+sbt-checkstyle-plugin is an AutoPlugin, so there is no need to modify the `build.sbt` file to enable it.
+
+If you want to modify any of the default settings, you should add the following import to `build.sbt`, however:
 
 ```scala
 import com.etsy.sbt.checkstyle._
-
-Checkstyle.checkstyleSettings
 ```
 
 ## Usage
@@ -65,8 +65,6 @@ The `xsltTransformations` setting allows applying XSLT transformations to the XM
 
 You can set `xsltTransformations` like so in `build.sbt`:
 ```scala
-import com.etsy.sbt.checkstyle._
-
 Checkstyle.xsltTransformations := {
   Some(Set(XSLTSettings(baseDirectory(_ / "checkstyle-noframes.xml").value, target(_ / "checkstyle-report.html").value)))
 }

src/main/scala/com/etsy/sbt/checkstyle/Checkstyle.scala

@@ -2,53 +2,22 @@ package com.etsy.sbt.checkstyle
 
 import javax.xml.transform.stream.StreamSource
 
+import com.etsy.sbt.checkstyle.CheckstyleSeverityLevel.CheckstyleSeverityLevel
 import com.puppycrawl.tools.checkstyle.Main.{main => CheckstyleMain}
 import net.sf.saxon.s9api.Processor
 import sbt.Def.Initialize
 import sbt.Keys._
 import sbt._
 
-import scala.io.Source
-
 /**
   * An SBT plugin to run checkstyle over Java code
   *
   * @author Andrew Johnson <ajohnson@etsy.com>
   * @author Alejandro Rivera <alejandro.rivera.lopez@gmail.com>
   * @author Joseph Earl <joe@josephearl.co.uk>
   */
-object Checkstyle extends Plugin {
-  sealed abstract class CheckstyleConfig(val location: String) {
-    def read(resources: Seq[File]): String
-  }
-
-  object CheckstyleConfig {
-    case class URL(url: String) extends CheckstyleConfig(url) {
-      override def read(resources: Seq[sbt.File]): String = Source.fromURL(url).mkString
-    }
-
-    case class File(path: String) extends CheckstyleConfig(path) {
-      override def read(resources: Seq[sbt.File]): String = Source.fromFile(path).mkString
-    }
-
-    case class Classpath(name: String) extends CheckstyleConfig(name) {
-      override def read(resources: Seq[sbt.File]): String = {
-        val classpath = resources.map((f) => f.toURI.toURL)
-        val loader = new java.net.URLClassLoader(classpath.toArray, getClass.getClassLoader)
-        Source.fromInputStream(loader.getResourceAsStream(name)).mkString
-      }
-    }
-  }
-
-  object CheckstyleSeverityLevel extends Enumeration {
-    type CheckstyleSeverityLevel = Value
-    val Ignore = Value("ignore")
-    val Info = Value("info")
-    val Warning = Value("warning")
-    val Error = Value("error")
-  }
-
-  import Checkstyle.CheckstyleSeverityLevel._
+object Checkstyle extends AutoPlugin {
+  override def trigger: PluginTrigger = allRequirements
 
   val checkstyle = TaskKey[Unit]("checkstyle", "Runs checkstyle")
   val outputFile = SettingKey[File]("checkstyle-target", "The location of the generated checkstyle report")
@@ -166,7 +135,7 @@ object Checkstyle extends Plugin {
     }
   }
 
-  val checkstyleSettings: Seq[Def.Setting[_]] = Seq(
+  override def projectSettings: Seq[Def.Setting[_]] = Seq(
     outputFile <<= target(_ / "checkstyle-report.xml"),
     outputFile in Test <<= target(_ / "checkstyle-test-report.xml"),
     configLocation := CheckstyleConfig.File("checkstyle-config.xml"),

src/main/scala/com/etsy/sbt/checkstyle/CheckstyleConfig.scala

@@ -0,0 +1,27 @@
+package com.etsy.sbt.checkstyle
+
+import sbt.File
+
+import scala.io.Source
+
+sealed abstract class CheckstyleConfig(val location: String) {
+    def read(resources: Seq[File]): String
+  }
+
+  object CheckstyleConfig {
+    case class URL(url: String) extends CheckstyleConfig(url) {
+      override def read(resources: Seq[sbt.File]): String = Source.fromURL(url).mkString
+    }
+
+    case class File(path: String) extends CheckstyleConfig(path) {
+      override def read(resources: Seq[sbt.File]): String = Source.fromFile(path).mkString
+    }
+
+    case class Classpath(name: String) extends CheckstyleConfig(name) {
+      override def read(resources: Seq[sbt.File]): String = {
+        val classpath = resources.map((f) => f.toURI.toURL)
+        val loader = new java.net.URLClassLoader(classpath.toArray, getClass.getClassLoader)
+        Source.fromInputStream(loader.getResourceAsStream(name)).mkString
+      }
+    }
+  }

src/main/scala/com/etsy/sbt/checkstyle/CheckstyleSeverityLevel.scala

@@ -0,0 +1,9 @@
+package com.etsy.sbt.checkstyle
+
+object CheckstyleSeverityLevel extends Enumeration {
+  type CheckstyleSeverityLevel = Value
+  val Ignore = Value("ignore")
+  val Info = Value("info")
+  val Warning = Value("warning")
+  val Error = Value("error")
+}

src/sbt-test/checkstyle/checkstyle-check-empty/build.sbt

@@ -6,5 +6,4 @@ organization := "com.etsy"
 
 import com.etsy.sbt.checkstyle._
 
-Checkstyle.checkstyleSettings
-Checkstyle.severityLevel := Some(Checkstyle.CheckstyleSeverityLevel.Error)
+Checkstyle.severityLevel := Some(CheckstyleSeverityLevel.Error)

src/sbt-test/checkstyle/checkstyle-check/build.sbt

@@ -6,6 +6,5 @@ organization := "com.etsy"
 
 import com.etsy.sbt.checkstyle._
 
-Checkstyle.checkstyleSettings
-Checkstyle.configLocation := Checkstyle.CheckstyleConfig.File("my-checkstyle-config.xml")
-Checkstyle.severityLevel := Some(Checkstyle.CheckstyleSeverityLevel.Error)
+Checkstyle.configLocation := CheckstyleConfig.File("my-checkstyle-config.xml")
+Checkstyle.severityLevel := Some(CheckstyleSeverityLevel.Error)

src/sbt-test/checkstyle/checkstyle-classpath-config-dependency/build.sbt

@@ -8,5 +8,4 @@ libraryDependencies += "com.puppycrawl.tools" % "checkstyle" % "6.13"
 
 import com.etsy.sbt.checkstyle._
 
-Checkstyle.checkstyleSettings
-Checkstyle.configLocation := Checkstyle.CheckstyleConfig.Classpath("google_checks.xml")
+Checkstyle.configLocation := CheckstyleConfig.Classpath("google_checks.xml")

src/sbt-test/checkstyle/checkstyle-classpath-config/build.sbt

@@ -6,5 +6,4 @@ organization := "com.etsy"
 
 import com.etsy.sbt.checkstyle._
 
-Checkstyle.checkstyleSettings
-Checkstyle.configLocation := Checkstyle.CheckstyleConfig.Classpath("com/etsy/sbt/google_checks.xml")
+Checkstyle.configLocation := CheckstyleConfig.Classpath("com/etsy/sbt/google_checks.xml")

src/sbt-test/checkstyle/checkstyle-integration-test/build.sbt

@@ -10,9 +10,6 @@ Defaults.itSettings
 
 import com.etsy.sbt.checkstyle._
 
-Checkstyle.configLocation := Checkstyle.CheckstyleConfig.File("my-checkstyle-config.xml")
-Checkstyle.checkstyleSettings ++ Seq(
-  Checkstyle.configLocation := Checkstyle.CheckstyleConfig.File("test-checkstyle-config.xml"),
-  Checkstyle.checkstyle       in IntegrationTest <<= Checkstyle.checkstyleTask(IntegrationTest),
-  Checkstyle.outputFile in IntegrationTest <<= target(_ / "checkstyle-integration-test-report.xml")
-)
+Checkstyle.configLocation := CheckstyleConfig.File("my-checkstyle-config.xml")
+Checkstyle.checkstyle in IntegrationTest <<= Checkstyle.checkstyleTask(IntegrationTest)
+Checkstyle.outputFile in IntegrationTest <<= target(_ / "checkstyle-integration-test-report.xml")

src/sbt-test/checkstyle/checkstyle-remote-config/build.sbt

@@ -6,6 +6,5 @@ organization := "com.etsy"
 
 import com.etsy.sbt.checkstyle._
 
-Checkstyle.checkstyleSettings
 Checkstyle.configLocation :=
-  Checkstyle.CheckstyleConfig.URL("https://raw.githubusercontent.com/etsy/sbt-checkstyle-plugin/master/src/sbt-test/checkstyle/checkstyle/checkstyle-config.xml")
+  CheckstyleConfig.URL("https://raw.githubusercontent.com/etsy/sbt-checkstyle-plugin/master/src/sbt-test/checkstyle/checkstyle/checkstyle-config.xml")

src/sbt-test/checkstyle/checkstyle-test/build.sbt

@@ -2,8 +2,4 @@ version := "0.1"
 
 name := "checkstyle-test"
 
-organization := "com.etsy"
-
-import com.etsy.sbt.checkstyle._
-
-Checkstyle.checkstyleSettings
+organization := "com.etsy"

src/sbt-test/checkstyle/checkstyle/build.sbt

@@ -6,5 +6,4 @@ organization := "com.etsy"
 
 import com.etsy.sbt.checkstyle._
 
-Checkstyle.checkstyleSettings
 Checkstyle.configLocation := CheckstyleConfig.File("checkstyle-config.xml")

src/sbt-test/checkstyle/xslt/build.sbt

@@ -6,7 +6,6 @@ organization := "com.etsy"
 
 import com.etsy.sbt.checkstyle._
 
-Checkstyle.checkstyleSettings
 Checkstyle.xsltTransformations := {
   Some(Set(XSLTSettings(baseDirectory(_ / "checkstyle-noframes.xml").value, target(_ / "checkstyle-report.html").value)))
 }