Kotlin support and libs.versions (#244)

Author: will-molloy

README.md

@@ -3,14 +3,14 @@
 [![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 projects using Gradle
+template repo for Java/Kotlin projects using Gradle
 
 ## Features
 
 - JDK 21 ([Amazon Corretto](https://aws.amazon.com/corretto/))
-- Gradle 8
+- [Gradle 8](https://github.com/gradle/gradle) with Kotlin DSL
 - [GitHub Actions](https://github.com/features/actions) CI/CD
-- Automatic code formatting via [Spotless](https://github.com/diffplug/spotless)
+- 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))
 - 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

@@ -5,39 +5,57 @@ import com.github.spotbugs.snom.SpotBugsExtension
 import com.github.spotbugs.snom.SpotBugsTask
 import org.gradle.api.tasks.testing.logging.TestExceptionFormat
 import org.gradle.api.tasks.testing.logging.TestLogEvent
+import org.jetbrains.kotlin.gradle.dsl.KotlinJvmProjectExtension
 
 logger.quiet("Java version: ${JavaVersion.current()}")
 logger.quiet("Gradle version: ${gradle.gradleVersion}")
 
 plugins {
   id("java-library")
-  id("com.diffplug.gradle.spotless") version "6.25.0" apply (false)
-  id("com.github.spotbugs") version "6.0.15" apply (false)
-  id("com.asarkar.gradle.build-time-tracker") version "4.3.0"
+  kotlin("jvm") version libs.versions.kotlin
+  alias(libs.plugins.spotless)
+  alias(libs.plugins.spotbugs)
+  alias(libs.plugins.buildtimetracker)
 }
 
 allprojects {
   group = "com.willmolloy"
   repositories {
     mavenCentral()
   }
-}
 
-subprojects {
   apply(plugin = "java")
   configure<JavaPluginExtension> {
     sourceCompatibility = JavaVersion.VERSION_21
     targetCompatibility = JavaVersion.VERSION_21
   }
 
+  apply(plugin = "kotlin")
+  configure<KotlinJvmProjectExtension> {
+    jvmToolchain(21)
+  }
+
   apply(plugin = "com.diffplug.spotless")
   configure<SpotlessExtension> {
     java {
       removeUnusedImports()
       googleJavaFormat()
+      trimTrailingWhitespace()
+      endWithNewline()
+    }
+    kotlin {
+      ktlint()
+      trimTrailingWhitespace()
+      endWithNewline()
+    }
+    kotlinGradle {
+      ktlint().editorConfigOverride(mapOf("ktlint_standard_no-empty-file" to "disabled"))
+      trimTrailingWhitespace()
+      endWithNewline()
     }
   }
 
+  // TODO this doesn't work on Kotlin, look into Detekt?
   apply(plugin = "checkstyle")
   configure<CheckstyleExtension> {
     toolVersion = "10.12.0"
@@ -68,17 +86,19 @@ subprojects {
       showExceptions = true
       showCauses = true
       showStackTraces = true
-      afterSuite(KotlinClosure2({ desc: TestDescriptor, result: TestResult ->
-        if (desc.parent == null) {
-          println(
-            "Results: ${result.resultType} " +
+      afterSuite(
+        KotlinClosure2({ desc: TestDescriptor, result: TestResult ->
+          if (desc.parent == null) {
+            println(
+              "Results: ${result.resultType} " +
                 "(${result.testCount} test${if (result.testCount > 1) "s" else ""}, " +
                 "${result.successfulTestCount} passed, " +
                 "${result.failedTestCount} failed, " +
-                "${result.skippedTestCount} skipped)"
-          )
-        }
-      }))
+                "${result.skippedTestCount} skipped)",
+            )
+          }
+        }),
+      )
     }
     finalizedBy(tasks.withType<JacocoReport>())
   }
@@ -102,20 +122,23 @@ subprojects {
   }
 
   dependencies {
-    implementation("org.apache.logging.log4j:log4j-core:2.23.1")
-    implementation("org.apache.logging.log4j:log4j-api:2.23.1")
-    implementation("org.apache.logging.log4j:log4j-slf4j2-impl:2.23.1")
-    implementation("com.github.spotbugs:spotbugs-annotations:4.8.5")
-    implementation("com.google.guava:guava:33.2.0-jre")
+    implementation(rootProject.libs.log4j.core)
+    implementation(rootProject.libs.log4j.api)
+    implementation(rootProject.libs.log4j.slf4j2)
+    implementation(rootProject.libs.spotbugs.annotations)
+    implementation(rootProject.libs.guava)
 
-    testImplementation("org.junit.jupiter:junit-jupiter:5.10.2")
-    testImplementation("com.google.truth:truth:1.4.2")
-    testImplementation("org.mockito:mockito-core:5.12.0")
-    testImplementation("org.mockito:mockito-junit-jupiter:5.12.0")
+    testImplementation(rootProject.libs.junit)
+    testImplementation(rootProject.libs.truth)
+    testImplementation(rootProject.libs.mockito.core)
+    testImplementation(rootProject.libs.mockito.junit)
 
     configurations.all {
-      exclude("org.assertj")
-      exclude("junit")
+      exclude(group = "org.assertj")
+      exclude(group = "junit")
+      resolutionStrategy {
+        force("com.google.guava:guava:${rootProject.libs.versions.guava.get()}") // exclude android version
+      }
     }
   }
 }

hello-world/build.gradle.kts example-java/build.gradle.ktshello-world/build.gradle.kts renamed to example-java/build.gradle.kts

@@ -1,5 +1,5 @@
 plugins {
-  id("org.unbroken-dome.test-sets") version "4.1.0"
+  alias(libs.plugins.testsets)
 }
 
 testSets {

…illmolloy/HelloWorldIntegrationTest.java …illmolloy/HelloWorldIntegrationTest.javahello-world/src/integrationTest/java/com/willmolloy/HelloWorldIntegrationTest.java renamed to example-java/src/integrationTest/java/com/willmolloy/HelloWorldIntegrationTest.java hello-world/src/integrationTest/java/com/willmolloy/HelloWorldIntegrationTest.java renamed to example-java/src/integrationTest/java/com/willmolloy/HelloWorldIntegrationTest.java

@@ -12,7 +12,7 @@
 class HelloWorldIntegrationTest {
 
   @Test
-  void test() {
+  void test_hello() {
     assertThat(new HelloWorld().hello("world")).isEqualTo("Hello world!");
   }
 }

…main/java/com/willmolloy/HelloWorld.java …main/java/com/willmolloy/HelloWorld.javahello-world/src/main/java/com/willmolloy/HelloWorld.java renamed to example-java/src/main/java/com/willmolloy/HelloWorld.java hello-world/src/main/java/com/willmolloy/HelloWorld.java renamed to example-java/src/main/java/com/willmolloy/HelloWorld.java

@@ -9,8 +9,7 @@
  * @author <a href=https://willmolloy.com>Will Molloy</a>
  */
 class HelloWorld {
-
-  private final Logger log = LogManager.getLogger();
+  private static final Logger log = LogManager.getLogger();
 
   String hello(String text) {
     log.debug("Hello {}!", text);

hello-world/src/main/resources/log4j2.xml …ample-java/src/main/resources/log4j2.xmlhello-world/src/main/resources/log4j2.xml renamed to example-java/src/main/resources/log4j2.xml hello-world/src/main/resources/log4j2.xml renamed to example-java/src/main/resources/log4j2.xml

@@ -13,4 +13,4 @@
 
     <Logger name="com.willmolloy" level="debug"/>
   </Loggers>
-</Configuration>
+</Configuration>

…/java/com/willmolloy/HelloWorldTest.java …/java/com/willmolloy/HelloWorldTest.javahello-world/src/test/java/com/willmolloy/HelloWorldTest.java renamed to example-java/src/test/java/com/willmolloy/HelloWorldTest.java hello-world/src/test/java/com/willmolloy/HelloWorldTest.java renamed to example-java/src/test/java/com/willmolloy/HelloWorldTest.java

@@ -12,7 +12,7 @@
 class HelloWorldTest {
 
   @Test
-  void test() {
+  void test_hello() {
     assertThat(new HelloWorld().hello("world")).isEqualTo("Hello world!");
   }
 }

example-kotlin/build.gradle.kts

@@ -0,0 +1 @@
+

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

@@ -0,0 +1,12 @@
+package com.willmolloy
+
+/**
+ * Example main src.
+ *
+ * @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

@@ -0,0 +1,14 @@
+package com.willmolloy
+
+import com.google.common.truth.Truth.assertThat
+import org.junit.jupiter.api.Test
+
+/**
+ * Unit tests for [HelloWorld].
+ */
+class HelloWorldTest {
+  @Test
+  fun `test hello`() {
+    assertThat(HelloWorld().hello("world")).isEqualTo("Hello world!")
+  }
+}