Add Kotlin publishing and testing examples (#3589)

Another addition for #3451: it adds `publishing` and `testing` examples
for Kotlin.

The only thing that needs to be mentioned is test filtering in Kotest:
it doesn't have `package.class.method` format to do the filtering,
instead it is using `specs` + `classes` parameters (see
[here](https://kotest.io/docs/framework/conditional/conditional-tests-with-gradle.html)).

Also `mockito-kotlin` requires JVM bytecode target to be 11.

Co-authored-by: 0xnm <0xnm@users.noreply.github.com>
Co-authored-by: Li Haoyi <haoyi.sg@gmail.com>

example/kotlinlib/publishing/2-publish-module/build.mill

@@ -0,0 +1,34 @@
+//// SNIPPET:BUILD
+package build
+import mill._, kotlinlib._, publish._
+
+object foo extends KotlinModule with PublishModule {
+
+  def mainClass = Some("foo.FooKt")
+
+  def kotlinVersion = "1.9.24"
+
+  def publishVersion = "0.0.1"
+
+  def pomSettings = PomSettings(
+    description = "Hello",
+    organization = "com.lihaoyi",
+    url = "https://github.com/lihaoyi/example",
+    licenses = Seq(License.MIT),
+    versionControl = VersionControl.github("lihaoyi", "example"),
+    developers = Seq(Developer("lihaoyi", "Li Haoyi", "https://github.com/lihaoyi"))
+  )
+}
+
+// This is an example `KotlinModule` with added publishing capabilities via
+// `PublishModule`. This requires that you define an additional
+// `publishVersion` and `pomSettings` with the relevant metadata, and provides
+// the `.publishLocal` and `publishSigned` tasks for publishing locally to the
+// machine or to the central maven repository
+
+/** Usage
+
+> mill foo.publishLocal
+Publishing Artifact(com.lihaoyi,foo,0.0.1) to ivy repo...
+
+*/

example/kotlinlib/publishing/2-publish-module/foo/src/foo/Foo.kt

@@ -0,0 +1,3 @@
+package foo
+
+fun main(args: Array<String>) = println("Hello World")

example/kotlinlib/testing/1-test-suite/bar/src/bar/Bar.kt

@@ -0,0 +1,9 @@
+package bar
+
+open class Bar {
+
+    fun hello(): String = "Hello World"
+
+}
+
+fun main(args: Array<String>) = println(Bar().hello())

example/kotlinlib/testing/1-test-suite/bar/test/src/bar/BarTests.kt

@@ -0,0 +1,34 @@
+package bar
+
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.string.shouldStartWith
+import io.kotest.matchers.string.shouldEndWith
+import org.mockito.kotlin.doReturn
+import org.mockito.kotlin.mock
+import org.mockito.kotlin.verify
+import org.mockito.kotlin.whenever
+
+class BarTests : FunSpec({
+
+    test("hello") {
+        val result = Bar().hello()
+        result shouldStartWith "Hello"
+    }
+
+    test("world") {
+        val result = Bar().hello()
+        result shouldEndWith "World"
+    }
+
+    test("mockito") {
+        val mockBar = mock<Bar>()
+
+        whenever(mockBar.hello()) doReturn "Hello Mockito World"
+
+        val result = mockBar.hello()
+
+        result shouldBe "Hello Mockito World"
+        verify(mockBar).hello()
+    }
+})

example/kotlinlib/testing/1-test-suite/build.mill

@@ -0,0 +1,44 @@
+//// SNIPPET:BUILD1
+package build
+import mill._, kotlinlib._
+
+object foo extends KotlinModule {
+
+  def mainClass = Some("foo.FooKt")
+
+  def kotlinVersion = "1.9.24"
+
+  object test extends KotlinModuleTests {
+    def testFramework = "com.github.sbt.junit.jupiter.api.JupiterFramework"
+    def ivyDeps = Agg(
+      ivy"com.github.sbt.junit:jupiter-interface:0.11.4",
+      ivy"io.kotest:kotest-runner-junit5-jvm:5.9.1",
+      ivy"org.mockito.kotlin:mockito-kotlin:5.4.0"
+    )
+
+    // This is needed because of the "mockito-kotlin"
+    def kotlincOptions = super.kotlincOptions() ++ Seq("-jvm-target", "11")
+  }
+}
+// This build defines a single module with a test suite, configured to use
+// "JUnit" + "Kotest" as the testing framework, along with Mockito. Test suites are themselves
+// ``KotlinModule``s, nested within the enclosing module,
+//// SNIPPET:BUILD2
+
+object bar extends KotlinModule {
+
+  def mainClass = Some("bar.BarKt")
+
+  def kotlinVersion = "1.9.24"
+
+  object test extends KotlinModuleTests with TestModule.Junit5 {
+    def ivyDeps = super.ivyDeps() ++ Agg(
+      ivy"io.kotest:kotest-runner-junit5-jvm:5.9.1",
+      ivy"org.mockito.kotlin:mockito-kotlin:5.4.0"
+    )
+
+    // This is needed because of the "mockito-kotlin"
+    def kotlincOptions = super.kotlincOptions() ++ Seq("-jvm-target", "11")
+  }
+}
+

example/kotlinlib/testing/1-test-suite/foo/src/foo/Foo.kt

@@ -0,0 +1,9 @@
+package foo
+
+open class Foo {
+
+    fun hello(): String = "Hello World"
+
+}
+
+fun main(args: Array<String>) = println(Foo().hello())

example/kotlinlib/testing/1-test-suite/foo/test/src/foo/FooTests.kt

@@ -0,0 +1,34 @@
+package foo
+
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.string.shouldStartWith
+import io.kotest.matchers.string.shouldEndWith
+import org.mockito.kotlin.doReturn
+import org.mockito.kotlin.mock
+import org.mockito.kotlin.verify
+import org.mockito.kotlin.whenever
+
+class FooTests : FunSpec({
+
+    test("hello") {
+        val result = Foo().hello()
+        result shouldStartWith "Hello"
+    }
+
+    test("world") {
+        val result = Foo().hello()
+        result shouldEndWith "World"
+    }
+
+    test("mockito") {
+        val mockFoo = mock<Foo>()
+
+        whenever(mockFoo.hello()) doReturn "Hello Mockito World"
+
+        val result = mockFoo.hello()
+
+        result shouldBe "Hello Mockito World"
+        verify(mockFoo).hello()
+    }
+})

example/kotlinlib/testing/2-test-deps/baz/src/baz/Baz.kt

@@ -0,0 +1,5 @@
+package baz
+
+object Baz {
+    const val VALUE = 123
+}

example/kotlinlib/testing/2-test-deps/baz/test/src/baz/BazTestUtils.kt

@@ -0,0 +1,11 @@
+package baz
+
+object BazTestUtils {
+
+    fun bazAssertEquals(x: Any, y: Any) {
+        println("Using BazTestUtils.bazAssertEquals")
+        if (x != y) {
+            throw AssertionError("Expected $y, but got $x")
+        }
+    }
+}

example/kotlinlib/testing/2-test-deps/baz/test/src/baz/BazTests.kt

@@ -0,0 +1,12 @@
+package baz
+
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.shouldBe
+import com.google.common.math.IntMath
+
+class BazTests : FunSpec({
+
+    test("simple") {
+        BazTestUtils.bazAssertEquals(Baz.VALUE, IntMath.mean(122, 124))
+    }
+})

example/kotlinlib/testing/2-test-deps/build.mill

@@ -0,0 +1,30 @@
+//// SNIPPET:BUILD
+package build
+import mill._, kotlinlib._
+
+object qux extends KotlinModule {
+
+  def kotlinVersion = "1.9.24"
+
+  def moduleDeps = Seq(baz)
+
+  object test extends KotlinModuleTests with TestModule.Junit5 {
+    def moduleDeps = super.moduleDeps ++ Seq(baz.test)
+    def ivyDeps = super.ivyDeps() ++ Agg(
+      ivy"io.kotest:kotest-runner-junit5-jvm:5.9.1",
+      ivy"com.google.guava:guava:33.3.0-jre"
+    )
+  }
+}
+
+object baz extends KotlinModule {
+
+  def kotlinVersion = "1.9.24"
+
+  object test extends KotlinModuleTests with TestModule.Junit5 {
+    def ivyDeps = super.ivyDeps() ++ Agg(
+      ivy"io.kotest:kotest-runner-junit5-jvm:5.9.1",
+      ivy"com.google.guava:guava:33.3.0-jre"
+    )
+  }
+}

example/kotlinlib/testing/2-test-deps/qux/src/qux/Qux.kt

@@ -0,0 +1,5 @@
+package qux
+
+object Qux {
+    const val VALUE = "xyz"
+}

example/kotlinlib/testing/2-test-deps/qux/test/src/qux/QuxTests.kt

@@ -0,0 +1,12 @@
+package qux
+
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.shouldBe
+import com.google.common.base.Ascii
+
+class QuxTests : FunSpec({
+
+    test("simple") {
+        baz.BazTestUtils.bazAssertEquals(Ascii.toLowerCase("XYZ"), Qux.VALUE)
+    }
+})

example/kotlinlib/testing/3-integration-suite/build.mill

@@ -0,0 +1,21 @@
+//// SNIPPET:BUILD3
+package build
+import mill._, kotlinlib._
+object qux extends KotlinModule {
+
+  def kotlinVersion = "1.9.24"
+
+  object test extends KotlinModuleTests with TestModule.Junit5 {
+    def ivyDeps = super.ivyDeps() ++ Agg(
+      ivy"io.kotest:kotest-runner-junit5-jvm:5.9.1"
+    )
+  }
+  object integration extends KotlinModuleTests with TestModule.Junit5 {
+    def ivyDeps = super.ivyDeps() ++ Agg(
+      ivy"io.kotest:kotest-runner-junit5-jvm:5.9.1"
+    )
+  }
+}
+
+// The integration suite is just another regular test module within the parent KotlinModule
+// (This example also demonstrates using Junit 5 instead of Junit 4)

example/kotlinlib/testing/3-integration-suite/qux/integration/src/qux/QuxIntegrationTests.kt

@@ -0,0 +1,12 @@
+package qux
+
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.shouldBe
+
+class QuxIntegrationTests : FunSpec({
+
+    test("helloworld") {
+        val result = Qux.hello()
+        result shouldBe "Hello World"
+    }
+})

example/kotlinlib/testing/3-integration-suite/qux/src/qux/Qux.kt

@@ -0,0 +1,7 @@
+package qux
+
+object Qux {
+    fun main(args: Array<String>) = println(hello())
+
+    fun hello(): String = "Hello World"
+}

example/kotlinlib/testing/3-integration-suite/qux/test/src/qux/QuxTests.kt

@@ -0,0 +1,19 @@
+package qux
+
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.string.shouldStartWith
+import io.kotest.matchers.string.shouldEndWith
+
+class QuxTests : FunSpec({
+
+    test("hello") {
+        val result = Qux.hello()
+        result shouldStartWith "Hello"
+    }
+
+    test("world") {
+        val result = Qux.hello()
+        result shouldEndWith "World"
+    }
+})

example/package.mill

@@ -42,6 +42,8 @@ object `package` extends RootModule with Module {
     object builds extends Cross[ExampleCrossModuleKotlin](build.listIn(millSourcePath / "builds"))
     object linting extends Cross[ExampleCrossModuleKotlin](build.listIn(millSourcePath / "linting"))
     object module extends Cross[ExampleCrossModuleKotlin](build.listIn(millSourcePath / "module"))
+    object publishing extends Cross[ExampleCrossModuleKotlin](build.listIn(millSourcePath / "publishing"))
+    object testing extends Cross[ExampleCrossModuleKotlin](build.listIn(millSourcePath / "testing"))
   }
   object scalalib extends Module {
     object basic extends Cross[ExampleCrossModule](build.listIn(millSourcePath / "basic"))
@@ -77,6 +79,16 @@ object `package` extends RootModule with Module {
         .replace("bar.BarTests.escaping", "bar.BarTestsescaping")
       case "4-builtin-commands" => line.replace("compile.dest/zinc", "compile.dest/kotlin.analysis.dummy")
       case "5-resources" => line.replace("FooTests.simple", "FooTestssimple")
+      case "1-test-suite" => line
+        .replace("mill bar.test bar.BarTests.hello", "kotest_filter_tests='hello' kotest_filter_specs='bar.BarTests' ./mill bar.test")
+        .replace("FooTests.hello", "FooTestshello")
+        .replace("FooTests.world", "FooTestsworld")
+        .replace("BarTests.hello", "BarTestshello")
+        .replace("BarTests.world", "BarTestsworld")
+        .replace("compiling 1 ... source...", "Compiling 1 ... source...")
+      case "2-test-deps" => line
+        .replace("qux.QuxTests.simple", "qux.QuxTestssimple")
+        .replace("baz.BazTests.simple", "baz.BazTestssimple")
       case _ => line
     }
   }