Set :poko-tests JVM toolchain version via CI (#311)

* Remove JDK-specific :poko-tests variants
* Update :poko-tests:performance
* Update CI action to test on older JDKs separately
* Delete unused old jvmToolchain helper from :poko-tests
* Only run build-sample once on CI

.github/workflows/ci.yml

@@ -15,11 +15,7 @@ jobs:
         uses: actions/setup-java@v4
         with:
           distribution: zulu
-          java-version: |
-            8
-            11
-            17
-            21
+          java-version: 21
 
       - name: Set up Gradle
         uses: gradle/actions/setup-gradle@v3
@@ -36,20 +32,42 @@ jobs:
           path: ~/.m2/repository/dev/drewhamilton/poko/
           if-no-files-found: error
 
-  build-sample:
+  test-with-jdk:
     runs-on: ubuntu-latest
-    needs: build
     strategy:
       matrix:
-        ci_java_version: [ 8, 11, 17, 21 ]
+        poko_tests_jvm_toolchain_version: [ 8, 11, 17 ]
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v4
+
+      - name: Install JDK ${{ matrix.poko_tests_jvm_toolchain_version }}
+        uses: actions/setup-java@v4
+        with:
+          distribution: zulu
+          java-version: |
+            ${{ matrix.poko_tests_jvm_toolchain_version }}
+            21
+
+      - name: Set up Gradle
+        uses: gradle/actions/setup-gradle@v3
+
+      - name: Test
+        run: ./gradlew :poko-tests:jvmTest :poko-tests:jvmK2Test --stacktrace
+        env:
+          poko_tests_jvm_toolchain_version: ${{ matrix.poko_tests_jvm_toolchain_version }}
+
+  build-sample:
+    runs-on: ubuntu-latest
+    needs: build
     steps:
       - name: Check out the repo
         uses: actions/checkout@v4
-      - name: Install JDK ${{ matrix.ci_java_version }}
+      - name: Install JDK
         uses: actions/setup-java@v4
         with:
           distribution: zulu
-          java-version: ${{ matrix.ci_java_version }}
+          java-version: 21
       - name: Download MavenLocal
         uses: actions/download-artifact@v4
         with:
@@ -61,8 +79,6 @@ jobs:
 
       - name: Build sample
         run: cd sample && ./gradlew build --stacktrace
-        env:
-          ci_java_version: ${{ matrix.ci_java_version }}
 
 env:
   GRADLE_OPTS: >-

poko-tests/build.gradle.kts

@@ -1,28 +1,13 @@
-import org.jetbrains.kotlin.gradle.dsl.KotlinMultiplatformExtension
 import org.jetbrains.kotlin.gradle.dsl.KotlinVersion
 import org.jetbrains.kotlin.gradle.plugin.KotlinTarget
 import org.jetbrains.kotlin.gradle.plugin.NATIVE_COMPILER_PLUGIN_CLASSPATH_CONFIGURATION_NAME
 import org.jetbrains.kotlin.gradle.plugin.PLUGIN_CLASSPATH_CONFIGURATION_NAME
-import org.jetbrains.kotlin.gradle.targets.jvm.KotlinJvmTarget
 
 plugins {
   alias(libs.plugins.kotlin.multiplatform)
 }
 
-fun KotlinMultiplatformExtension.jvm(
-  version: Int,
-  baseName: String = "jvm",
-): KotlinJvmTarget {
-  return jvm(baseName.replace("jvm", "jvm$version")) {
-    compilations.configureEach {
-      jvmToolchain(version)
-    }
-
-    // Dummy value required to disambiguate these targets' configurations.
-    // See https://kotlinlang.org/docs/multiplatform-set-up-targets.html#distinguish-several-targets-for-one-platform
-    attributes.attribute(Attribute.of("com.example.JvmTarget", Int::class.javaObjectType), version)
-  }
-}
+val jvmToolchainVersion: Int? = System.getenv()["poko_tests_jvm_toolchain_version"]?.toInt()
 
 fun <T : KotlinTarget> T.applyK2(): T {
   compilations.configureEach {
@@ -37,13 +22,8 @@ fun <T : KotlinTarget> T.applyK2(): T {
 }
 
 kotlin {
-  jvm(8)
-  jvm(8, "jvmK2").applyK2()
-  jvm(11)
-  jvm(11, "jvmK2").applyK2()
-  jvm(17)
-  jvm(17, "jvmK2").applyK2()
-  // Build JDK which should be latest:
+  jvmToolchainVersion?.let { jvmToolchain(it) }
+
   jvm()
   jvm("jvmK2").applyK2()
 

poko-tests/performance/build.gradle.kts

@@ -11,5 +11,4 @@ dependencies {
 tasks.named("test") {
     dependsOn(":poko-tests:compileProductionExecutableKotlinJs")
     dependsOn(":poko-tests:compileKotlinJvm")
-    dependsOn(":poko-tests:compileKotlinJvm11")
 }

poko-tests/performance/src/test/kotlin/JvmPerformanceTest.kt

@@ -2,7 +2,9 @@ import assertk.all
 import assertk.assertThat
 import assertk.assertions.contains
 import assertk.assertions.doesNotContain
+import org.junit.AssumptionViolatedException
 import org.junit.Test
+import org.objectweb.asm.ClassReader
 
 class JvmPerformanceTest {
     @Test fun `int property does not emit hashCode method invocation`() {
@@ -24,11 +26,22 @@ class JvmPerformanceTest {
     }
 
     @Test fun `toString uses invokedynamic on modern JDKs`() {
-        val classfile = jvmOutput("performance/IntAndLong.class", version = 11)
-        val bytecode = bytecodeToText(classfile.readBytes())
+        val classfile = jvmOutput("performance/IntAndLong.class")
+        val classReader = ClassReader(classfile.readBytes())
+        // Java 9 == class file major version 53:
+        classReader.assumeMinimumClassVersion(53)
+        val bytecode = classReader.toText()
         assertThat(bytecode).all {
             contains("INVOKEDYNAMIC makeConcatWithConstants")
             doesNotContain("StringBuilder")
         }
     }
+
+    private fun ClassReader.assumeMinimumClassVersion(version: Int) {
+        // Class file major version is a two-byte integer at offset 6:
+        val actualClassVersion = readShort(6)
+        if (actualClassVersion < version) {
+            throw AssumptionViolatedException("This test only works class version $version+")
+        }
+    }
 }

poko-tests/performance/src/test/kotlin/asm.kt

@@ -5,8 +5,12 @@ import org.objectweb.asm.util.Textifier
 import org.objectweb.asm.util.TraceClassVisitor
 
 fun bytecodeToText(bytecode: ByteArray): String {
+    return ClassReader(bytecode).toText()
+}
+
+fun ClassReader.toText(): String {
     val textifier = Textifier()
-    ClassReader(bytecode).accept(TraceClassVisitor(null, textifier, null), 0)
+    accept(TraceClassVisitor(null, textifier, null), 0)
 
     val writer = StringWriter()
     textifier.print(PrintWriter(writer))

poko-tests/performance/src/test/kotlin/sources.kt

@@ -1,7 +1,4 @@
 import java.io.File
 
-fun jvmOutput(relativePath: String, version: Int = -1): File {
-    val number = if (version == -1) "" else "$version"
-    return File("../build/classes/kotlin/jvm$number/main", relativePath)
-}
+fun jvmOutput(relativePath: String) = File("../build/classes/kotlin/jvm/main", relativePath)
 fun jsOutput() = File("../build/compileSync/js/main/productionExecutable/kotlin/Poko-poko-tests.js")