Initial Groovy setup (#5747)

I have been working on Groovy support since I would like to use Mill for
projects where tests are written in Spock/Groovy.

It is basically a modified version of the Kotlin support.

Whats currently working:
- Groovy compilation (tested with 4 & 5)
- Maven project layout with an additional convenience option to
configure Groovy for tests only
- JUnit5 test execution
- Spock tests
- CompileStatic
- Configure Bytecode Version and Preview


If anyone would like to provide feedback I would appreciate it. 

Pull request: #5747

Co-authored-by: Tobias Roeser <le.petit.fou@web.de>
Co-authored-by: Li Haoyi <haoyi.sg@gmail.com>

Author: 3 people

.github/workflows/run-tests.yml

@@ -157,6 +157,10 @@ jobs:
             millargs: "example.androidlib.__.shared.daemon"
             setup-android: true
 
+          - java-version: 17
+            millargs: "'example.groovylib.__.shared.daemon'"
+            setup-android: true
+
           - java-version: 17
             millargs: "example.thirdparty.android-compose-samples.packaged.daemon"
             setup-android: true

core/api/daemon/src/mill/api/daemon/internal/GroovyModuleApi.scala

@@ -0,0 +1,4 @@
+package mill.api.daemon.internal
+
+@mill.api.daemon.experimental
+trait GroovyModuleApi extends JavaModuleApi

core/api/daemon/src/mill/api/daemon/internal/bsp/BspModuleApi.scala

@@ -23,6 +23,7 @@ object BspModuleApi {
     val Java = "java"
     val Scala = "scala"
     val Kotlin = "kotlin"
+    val Groovy = "groovy"
   }
 
   /** Used to define the [[BspBuildTarget.tags]] field. */

core/eval/src/mill/eval/ScriptModuleInit.scala

@@ -53,6 +53,7 @@ class ScriptModuleInit extends ((String, Evaluator) => Seq[Result[ExternalModule
           case "java" => Result.Success("mill.script.JavaModule")
           case "kt" => Result.Success("mill.script.KotlinModule")
           case "scala" => Result.Success("mill.script.ScalaModule")
+          case "groovy" => Result.Success("mill.script.GroovyModule")
           case _ =>
             Result.Failure(
               s"Script ${scriptFile.relativeTo(mill.api.BuildCtx.workspaceRoot)} has no `extends` clause configured and is of an unknown extension `${scriptFile.ext}`"

example/groovylib/basic/1-script/Foo.groovy

@@ -0,0 +1,11 @@
+class Foo {
+
+    static void main(String[] args) {
+        if(args == null || args.length != 1){
+            println "Specify exactly one parameter for greeting"
+            System.exit(1)
+        }
+
+        println "Hello ${args[0]}"
+    }
+}

example/groovylib/basic/1-script/build.mill

@@ -0,0 +1,32 @@
+//// SNIPPET:FILE
+/** See Also: Foo.groovy */
+//// SNIPPET:END
+
+//// SNIPPET:CMD
+/** Usage
+> ./mill Foo.groovy bar
+Compiling 1 Groovy sources to...
+Hello bar
+*/
+//// SNIPPET:END
+//// SNIPPET:MORE
+
+/** Usage
+> ./mill Foo.groovy:run bar
+Hello bar
+*/
+
+//// SNIPPET:END
+
+//// SNIPPET:RESOLVE
+/** Usage
+
+> ./mill resolve Foo.groovy:_
+Foo.groovy:run
+Foo.groovy:runMain
+Foo.groovy:compile
+Foo.groovy:assembly
+...
+
+*/
+//// SNIPPET:END

example/groovylib/basic/11-declarative/build.mill

@@ -0,0 +1,49 @@
+// This is a basic Mill build for a single `GroovyModule`, with one
+// third-party dependency and a test suite using the JUnit framework.
+//
+// This example project uses two third-party dependencies
+// - Groovy-Cli-Commons for CLI argument parsing
+// - Groovy-Xml for HTML templating and escaping
+// and uses them to wrap a given input string in HTML templates with proper escaping.
+//
+
+/** See Also: build.mill.yaml */
+/** See Also: test/package.mill.yaml */
+
+/** Usage
+
+> ./mill resolve _ # List what tasks are available to run
+assembly
+...
+compile
+...
+run
+...
+test
+
+*/
+
+/** Usage
+> ./mill run --text hello
+<h1>hello</h1>
+*/
+
+/** Usage
+> ./mill test
+Running Test Class foo.FooTest
+Test foo.FooTest#generate html created properly() finished...
+Test foo.FooTest#generated html is properly escaped() finished...
+Test foo.FooTest finished...
+
+*/
+
+/** Usage
+> ./mill assembly # bundle classfiles and libraries into a jar for deployment
+
+> ./mill show assembly # show the output of the assembly task
+".../out/assembly.dest/out.jar"
+
+> java -jar ./out/assembly.dest/out.jar --text hello
+<h1>hello</h1>
+
+*/

example/groovylib/basic/11-declarative/build.mill.yaml

@@ -0,0 +1,7 @@
+extends: [mill.groovylib.GroovyModule]
+groovyVersion: 5.0.3
+mvnDeps:
+  - org.apache.groovy:groovy-cli-commons
+  - org.apache.groovy:groovy-xml
+mainClass: foo.Foo
+groovyCompileTargetBytecode: '11'

example/groovylib/basic/11-declarative/src/foo/Foo.groovy

@@ -0,0 +1,32 @@
+package foo
+
+import groovy.xml.MarkupBuilder
+import groovy.cli.commons.CliBuilder
+
+class Foo {
+    static String generateHtml(String text) {
+        def writer = new StringWriter()
+        new MarkupBuilder(writer).h1 {
+            mkp.yield text
+        }
+        writer.toString()
+    }
+
+    static void main(String[] args) {
+        def cli = new CliBuilder(usage:'help')
+        cli.t(longOpt:'text', args: 1, 'Passes text to the HTML generation')
+        def options = cli.parse(args)
+
+        if (!options) {
+            return
+        }
+
+        if (options.h) {
+            cli.usage()
+            return
+        }
+
+        String textToProcess = options.t ?: "hello from main"
+        println generateHtml(textToProcess)
+    }
+}

example/groovylib/basic/11-declarative/test/package.mill.yaml

@@ -0,0 +1,4 @@
+extends: [build.GroovyTests, mill.javalib.TestModule.Junit5]
+jupiterVersion: 5.13.4
+mvnDeps:
+  - org.apache.groovy:groovy-test