Swap to ktfmt (googleStyle) for Kotlin code, but keep ktlint for Gradle scripts (#245)

Author: will-molloy

README.md

@@ -3,14 +3,17 @@
 [![build](https://github.com/will-molloy/java-template/actions/workflows/build.yml/badge.svg?branch=main&event=push)](https://github.com/will-molloy/java-template/actions/workflows/build.yml)
 [![codecov](https://codecov.io/gh/will-molloy/java-template/branch/main/graph/badge.svg)](https://codecov.io/gh/will-molloy/java-template)
 
-template repo for Java/Kotlin projects using Gradle
+template repo for Java/Kotlin Gradle projects
 
 ## Features
 
 - JDK 21 ([Amazon Corretto](https://aws.amazon.com/corretto/))
-- [Gradle 8](https://github.com/gradle/gradle) with Kotlin DSL
+- [Gradle 8](https://github.com/gradle/gradle) (Kotlin DSL)
 - [GitHub Actions](https://github.com/features/actions) CI/CD
-- Automatic code formatting via [Spotless](https://github.com/diffplug/spotless) ([`google-java-format`](https://github.com/google/google-java-format) and [`ktlint`](https://github.com/pinterest/ktlint))
+- Automatic code formatting via [Spotless](https://github.com/diffplug/spotless)
+  - Java: [`google-java-format`](https://github.com/google/google-java-format)
+  - Kotlin: [`ktfmt`](https://github.com/facebook/ktfmt)
+  - Kotlin Gradle: [`ktlint`](https://github.com/pinterest/ktlint)
 - Code style analysis via [Checkstyle](https://github.com/checkstyle/checkstyle)
 - Static analysis via [SpotBugs](https://spotbugs.github.io/)
 - Unit and integration test support via [JUnit 5](https://junit.org/junit5/) and [TestSets plugin](https://github.com/unbroken-dome/gradle-testsets-plugin)

build.gradle.kts

@@ -37,14 +37,16 @@ allprojects {
 
   apply(plugin = "com.diffplug.spotless")
   configure<SpotlessExtension> {
+    // https://github.com/diffplug/spotless/tree/main/plugin-gradle#java
     java {
       removeUnusedImports()
       googleJavaFormat()
       trimTrailingWhitespace()
       endWithNewline()
     }
+    // https://github.com/diffplug/spotless/tree/main/plugin-gradle#kotlin
     kotlin {
-      ktlint()
+      ktfmt().googleStyle()
       trimTrailingWhitespace()
       endWithNewline()
     }
@@ -55,7 +57,7 @@ allprojects {
     }
   }
 
-  // TODO this doesn't work on Kotlin, look into Detekt?
+  // TODO Kotlin alternative?
   apply(plugin = "checkstyle")
   configure<CheckstyleExtension> {
     toolVersion = "10.12.0"
@@ -137,7 +139,8 @@ allprojects {
       exclude(group = "org.assertj")
       exclude(group = "junit")
       resolutionStrategy {
-        force("com.google.guava:guava:${rootProject.libs.versions.guava.get()}") // exclude android version
+        // exclude android version
+        force("com.google.guava:guava:${rootProject.libs.versions.guava.get()}")
       }
     }
   }

example-java/build.gradle.kts

@@ -1,7 +1,3 @@
-plugins {
-  alias(libs.plugins.testsets)
-}
+plugins { alias(libs.plugins.testsets) }
 
-testSets {
-  create("integrationTest")
-}
+testSets { create("integrationTest") }

example-kotlin/src/main/kotlin/com/willmolloy/HelloWorld.kt

@@ -6,6 +6,7 @@ package com.willmolloy
  * @author <a href=https://willmolloy.com>Will Molloy</a>
  */
 class HelloWorld {
+
   fun hello(text: String): String {
     return "Hello $text!"
   }

example-kotlin/src/test/kotlin/com/willmolloy/HelloWorldTest.kt

@@ -3,10 +3,9 @@ package com.willmolloy
 import com.google.common.truth.Truth.assertThat
 import org.junit.jupiter.api.Test
 
-/**
- * Unit tests for [HelloWorld].
- */
+/** Unit tests for [HelloWorld]. */
 class HelloWorldTest {
+
   @Test
   fun `test hello`() {
     assertThat(HelloWorld().hello("world")).isEqualTo("Hello world!")