Move SampleClasses test utility to dedicated 'testing' sub-project

Author: mcculls

buildSrc/src/main/kotlin/java-common.gradle.kts

@@ -4,6 +4,7 @@ plugins {
   java
   jacoco
 
+  id("me.champeau.jmh")
   id("com.diffplug.spotless")
   id("com.github.spotbugs")
   id("pl.allegro.tech.build.axion-release")
@@ -15,6 +16,14 @@ repositories {
 
 version = rootProject.version
 
+dependencies {
+  compileOnly(libs.spotbugs.annotations)
+  testCompileOnly(libs.spotbugs.annotations)
+  testImplementation(libs.junit.jupiter)
+  testImplementation(libs.assertj.core)
+  testRuntimeOnly(libs.junit.launcher)
+}
+
 java {
   toolchain {
     languageVersion = JavaLanguageVersion.of(17)
@@ -32,14 +41,6 @@ tasks.javadoc {
   }
 }
 
-dependencies {
-  compileOnly(libs.spotbugs.annotations)
-  testCompileOnly(libs.spotbugs.annotations)
-  testImplementation(libs.junit.jupiter)
-  testImplementation(libs.assertj.core)
-  testRuntimeOnly(libs.junit.launcher)
-}
-
 tasks.named<Test>("test") {
   useJUnitPlatform()
 }
@@ -70,7 +71,6 @@ tasks.check { finalizedBy(tasks.jacocoTestReport) }
 spotless {
   java {
     target("src/**/*.java")
-
     importOrder()
     removeUnusedImports()
     googleJavaFormat()
@@ -79,6 +79,21 @@ spotless {
 
 spotbugs {
   useJavaToolchains = true
-
   omitVisitors = listOf("FindReturnRef")
 }
+
+// dependency configuration to help pull sample bytecode in for testing
+val sampleBytecode by configurations.creating {
+  isTransitive = false
+}
+
+// copy sample bytecode jars to a known location for testing/benchmarking
+val sampleBytecodeDir = layout.buildDirectory.dir("sampleBytecode")
+val copySampleBytecode = tasks.register<Copy>("sampleBytecode") {
+  val versionJarSuffix = "-[0-9.]*\\.jar$".toRegex()
+  rename { name -> name.replace(versionJarSuffix, ".jar") }
+  into(sampleBytecodeDir)
+  from(sampleBytecode)
+}
+tasks.test { dependsOn(copySampleBytecode) }
+tasks.jmh { dependsOn(copySampleBytecode) }

class-match/build.gradle.kts

@@ -1,28 +1,12 @@
 plugins {
   id("java-common")
-  id("me.champeau.jmh")
-}
-
-val sampleBytecode by configurations.creating {
-  isTransitive = false
 }
 
 dependencies {
   implementation(project(":utils"))
 
   sampleBytecode("org.ow2.asm:asm-test:9.8")
   sampleBytecode("org.springframework:spring-web:6.2.8")
-
+  jmh(project(":testing"))
   jmh(libs.asm)
 }
-
-// copy sample bytecode jars to a known location for testing/benchmarking
-val sampleBytecodeDir = layout.buildDirectory.dir("sampleBytecode")
-val copySampleBytecode = tasks.register<Copy>("sampleBytecode") {
-  val versionJarSuffix = "-[0-9.]*\\.jar$".toRegex()
-  rename { name -> name.replace(versionJarSuffix, ".jar") }
-  into(sampleBytecodeDir)
-  from(sampleBytecode)
-}
-tasks.test { dependsOn(copySampleBytecode) }
-tasks.jmh { dependsOn(copySampleBytecode) }

class-match/src/jmh/java/datadog/instrument/classmatch/ClassFileBenchmark.java

@@ -8,6 +8,7 @@
 import static org.objectweb.asm.Opcodes.ASM9;
 import static org.openjdk.jmh.annotations.Mode.AverageTime;
 
+import datadog.instrument.testing.SampleClasses;
 import java.util.ArrayList;
 import java.util.List;
 import org.objectweb.asm.AnnotationVisitor;

class-match/src/jmh/java/datadog/instrument/classmatch/ClassInfoCacheBenchmark.java

@@ -3,6 +3,7 @@
 import static java.util.concurrent.TimeUnit.MICROSECONDS;
 import static org.openjdk.jmh.annotations.Mode.AverageTime;
 
+import datadog.instrument.testing.SampleClasses;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.util.List;

class-match/src/jmh/java/datadog/instrument/classmatch/ClassNameFilterBenchmark.java

@@ -3,6 +3,7 @@
 import static java.util.concurrent.TimeUnit.MICROSECONDS;
 import static org.openjdk.jmh.annotations.Mode.AverageTime;
 
+import datadog.instrument.testing.SampleClasses;
 import java.util.List;
 import java.util.stream.Collectors;
 import org.openjdk.jmh.annotations.Benchmark;

class-match/src/jmh/java/datadog/instrument/classmatch/ClassNameTrieBenchmark.java

@@ -3,6 +3,7 @@
 import static java.util.concurrent.TimeUnit.MICROSECONDS;
 import static org.openjdk.jmh.annotations.Mode.AverageTime;
 
+import datadog.instrument.testing.SampleClasses;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;

settings.gradle.kts

@@ -1,5 +1,6 @@
 rootProject.name = "dd-instrument-java"
 
+include(":testing")
 include(":utils")
 include(":class-inject")
 include(":class-match")

testing/build.gradle.kts

@@ -0,0 +1,3 @@
+plugins {
+  id("java-common")
+}

class-match/src/jmh/java/datadog/instrument/classmatch/SampleClasses.java renamed to testing/src/main/java/datadog/instrument/testing/SampleClasses.java

@@ -1,4 +1,10 @@
-package datadog.instrument.classmatch;
+/*
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache-2.0 License.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/).
+ * Copyright 2025-Present Datadog, Inc.
+ */
+
+package datadog.instrument.testing;
 
 import java.io.ByteArrayOutputStream;
 import java.io.File;
@@ -10,9 +16,22 @@
 import java.util.jar.JarFile;
 import java.util.stream.Collectors;
 
-final class SampleClasses {
+/**
+ * Provides access to external bytecode declared using the {@code sampleBytecode} gradle dependency.
+ */
+public final class SampleClasses {
+
+  /** The directory containing the sample bytecode jars. */
+  public static final String SAMPLE_BYTECODE_DIRECTORY = "build/sampleBytecode/";
+
+  /**
+   * Loads all class bytecode from the named sample bytecode jar.
+   *
+   * @param sampleJar the name of the sample jar (without version)
+   * @return list of bytecode contained in the sample jar
+   */
   public static List<byte[]> load(String sampleJar) {
-    File sampleJarFile = new File("build/sampleBytecode/" + sampleJar);
+    File sampleJarFile = new File(SAMPLE_BYTECODE_DIRECTORY + sampleJar);
     byte[] buf = new byte[16384];
     ByteArrayOutputStream out = new ByteArrayOutputStream();
     try (JarFile sample = new JarFile(sampleJarFile)) {

utils/build.gradle.kts

@@ -1,6 +1,5 @@
 plugins {
   id("java-multiversion")
-  id("me.champeau.jmh")
 }
 
 tasks.withType<Test>().configureEach {