add hook for Groovy compilations to be processed as well

src/main/groovy/me/tatarka/RetrolambdaPlugin.groovy

@@ -21,6 +21,7 @@ import org.gradle.api.JavaVersion
 import org.gradle.api.Plugin
 import org.gradle.api.Project
 import org.gradle.api.plugins.ApplicationPlugin
+import org.gradle.api.plugins.GroovyPlugin
 import org.gradle.api.plugins.JavaPlugin
 /**
  * Created with IntelliJ IDEA.
@@ -50,6 +51,10 @@ public class RetrolambdaPlugin implements Plugin<Project> {
             project.apply plugin: RetrolambdaPluginJava
         }
 
+        project.plugins.withType(GroovyPlugin) {
+            project.apply plugin: RetrolambdaPluginGroovy
+        }
+
         project.plugins.withType(AppPlugin) {
             project.apply plugin: RetrolambdaPluginAndroid
         }

src/main/groovy/me/tatarka/RetrolambdaPluginGroovy.groovy

@@ -0,0 +1,79 @@
+/**
+ Copyright 2014 Evan Tatarka
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ */
+
+package me.tatarka
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.api.ProjectConfigurationException
+import org.gradle.api.tasks.SourceSet
+import org.gradle.api.tasks.compile.JavaCompile
+
+import static me.tatarka.RetrolambdaPlugin.checkIfExecutableExists
+/**
+ * Created with IntelliJ IDEA.
+ * User: evan
+ * Date: 8/4/13
+ * Time: 1:36 PM
+ * To change this template use File | Settings | File Templates.
+ */
+public class RetrolambdaPluginGroovy implements Plugin<Project> {
+    @Override
+    void apply(Project project) {
+        project.afterEvaluate {
+            project.sourceSets.all { SourceSet set ->
+                if (project.retrolambda.isIncluded(set.name)) {
+                    def name = set.name.capitalize()
+                    def taskName = "compileRetrolambdaGroovy$name"
+                    def oldOutputDir = set.output.classesDir
+                    def newOutputDir = project.file("$project.buildDir/retrolambda/$set.name")
+
+                    /* No compileJavaTaskName present, so re-use any modifications applied to compileJava and remap to Groovy */
+                    def compileGroovyTaskName = set.compileJavaTaskName.replace(/Java/,/Groovy/)
+                    def compileGroovyTask = project.tasks.getByName(compileGroovyTaskName)
+
+                    compileGroovyTask.destinationDir = newOutputDir
+                    def retrolambdaTask = project.task(taskName, dependsOn: compileGroovyTask, type: RetrolambdaTask) {
+                        inputDir = newOutputDir
+                        outputDir = oldOutputDir
+                        classpath = set.compileClasspath + project.files(newOutputDir)
+                        javaVersion = project.retrolambda.javaVersion
+                        jvmArgs = project.retrolambda.jvmArgs
+                        enabled = !set.allJava.isEmpty()
+                    }
+
+                    project.tasks.findByName(set.classesTaskName).dependsOn(retrolambdaTask)
+
+                    if (!project.retrolambda.onJava8) {
+                        // Set JDK 8 for compiler task
+                        compileGroovyTask.doFirst {
+                            it.options.fork = true
+                            it.options.forkOptions.executable = "${project.retrolambda.tryGetJdk()}/bin/javac"
+                        }
+                    }
+                }
+            }
+
+            project.tasks.getByName("test").doFirst {
+                if (project.retrolambda.onJava8) {
+                    //Ensure the tests run on java6/7
+                    def oldJava = "${project.retrolambda.tryGetOldJdk()}/bin/java"
+                    if (!checkIfExecutableExists(oldJava)) throw new ProjectConfigurationException("Cannot find executable: $oldJava", null)
+                    executable oldJava
+                }
+            }
+        }
+    }
+}