Add basic groovy code style validation.

IDK how well this would work on a gradle script but might be interesting to try on yarn or something.

.gitignore

@@ -20,3 +20,4 @@
 !/settings.gradle
 !/Jenkinsfile
 !/checkstyle.xml
+!/codenarc.groovy

build.gradle

@@ -7,6 +7,7 @@ plugins {
 	id 'groovy'
 	id 'checkstyle'
 	id 'jacoco'
+	id 'codenarc'
 	id "org.cadixdev.licenser" version "0.5.0"
 }
 
@@ -110,6 +111,11 @@ checkstyle {
 	toolVersion = '8.39'
 }
 
+codenarc {
+	toolVersion = "2.0.0"
+	configFile = file("codenarc.groovy")
+}
+
 gradlePlugin {
 	plugins {
 		fabricLoom {

codenarc.groovy

@@ -0,0 +1,66 @@
+ruleset {
+    UnnecessarySemicolon
+    BlockEndsWithBlankLine
+    BlockStartsWithBlankLine
+    ConsecutiveBlankLines
+    MissingBlankLineAfterImports
+    MissingBlankLineAfterPackage
+
+    // Braces
+    BracesForClass
+    BracesForForLoop
+    BracesForIfElse
+    BracesForMethod
+    BracesForTryCatchFinally
+
+    // Spaces
+    SpaceAfterCatch
+    SpaceAfterComma
+    SpaceAfterClosingBrace
+    SpaceAfterFor
+    SpaceAfterIf
+    SpaceAfterOpeningBrace
+    SpaceAfterSemicolon
+    SpaceAfterSwitch
+    SpaceAfterWhile
+    SpaceAroundClosureArrow
+    SpaceAroundMapEntryColon
+    SpaceAroundOperator
+    SpaceBeforeClosingBrace
+    SpaceBeforeOpeningBrace
+    TrailingWhitespace
+
+    // Groovyism - See: https://codenarc.org/codenarc-rules-groovyism.html
+    ClosureAsLastMethodParameter
+    ExplicitArrayListInstantiation
+    ExplicitCallToAndMethod
+    ExplicitCallToCompareToMethod
+    ExplicitCallToDivMethod
+    ExplicitCallToEqualsMethod
+    ExplicitCallToGetAtMethod
+    ExplicitCallToLeftShiftMethod
+    ExplicitCallToMinusMethod
+    ExplicitCallToMultiplyMethod
+    ExplicitCallToModMethod
+    ExplicitCallToOrMethod
+    ExplicitCallToPlusMethod
+    ExplicitCallToPowerMethod
+    ExplicitCallToRightShiftMethod
+    ExplicitCallToXorMethod
+    ExplicitHashMapInstantiation
+    ExplicitLinkedHashMapInstantiation
+    ExplicitHashSetInstantiation
+    ExplicitLinkedListInstantiation
+    ExplicitStackInstantiation
+    ExplicitTreeSetInstantiation
+    GetterMethodCouldBeProperty
+    GStringAsMapKey
+    GStringExpressionWithinString
+    CouldBeElvis
+    TernaryCouldBeElvis
+    FieldTypeRequired
+    MethodParameterTypeRequired
+
+    //Misc
+    LongLiteralWithLowerCaseL
+}

src/test/groovy/net/fabricmc/loom/AccessWidenerTest.groovy

@@ -43,7 +43,7 @@ class AccessWidenerTest extends Specification implements ProjectTestTrait, Archi
 			def result = create("build", gradle)
 		then:
 			result.task(":build").outcome == SUCCESS
-			getArchiveEntry("fabric-example-mod-1.0.0.jar", "modid.accesswidener") == expected().replaceAll('\r','')
+			getArchiveEntry("fabric-example-mod-1.0.0.jar", "modid.accesswidener") == expected().replaceAll('\r', '')
 		where:
 			gradle     | _
 			'6.8.3'    | _

src/test/groovy/net/fabricmc/loom/util/ProjectTestTrait.groovy

@@ -43,7 +43,7 @@ trait ProjectTestTrait {
 			throw new FileNotFoundException("Failed to find project directory at:" + baseProjectDir.absolutePath)
 		}
 
-		baseProjectDir.eachFileRecurse {file ->
+		baseProjectDir.eachFileRecurse { file ->
 			if (file.isDirectory()) {
 				return
 			}