Adopt Gradle test suites for smoke tests

Replace manual source set and configuration setup with native Gradle
JvmTestSuite. This aligns with upstream OpenTelemetry Java instrumentation
patterns (adopted in v1.24.0) and provides better IDE integration.

Changes:
- Remove manual sourceSets.create("smokeTest") configuration
- Remove manual configuration extensions (smokeTestImplementation, etc.)
- Add testing.suites block with JvmTestSuite registration
- Move dependencies into test suite DSL
- Preserve all existing behavior (environment matrix, system properties,
  test logging, nested test classes with @Environment annotations)

Test suite automatically creates smokeTestImplementation and other
configurations, simplifying the build logic while maintaining full
backward compatibility.

Author: trask

buildSrc/src/main/kotlin/ai.smoke-test.gradle.kts

@@ -8,19 +8,6 @@ plugins {
 
 val aiSmokeTest = extensions.create<AiSmokeTestExtension>("aiSmokeTest")
 
-sourceSets {
-  create("smokeTest") {
-    compileClasspath += sourceSets.main.get().output
-    runtimeClasspath += sourceSets.main.get().output
-  }
-}
-
-val smokeTestImplementation by configurations.getting {
-  extendsFrom(configurations.implementation.get())
-}
-
-configurations["smokeTestRuntimeOnly"].extendsFrom(configurations.runtimeOnly.get())
-
 // FIXME (trask) copy-pasted from ai.java-conventions.gradle
 java {
   toolchain {
@@ -66,20 +53,75 @@ dependencies {
   // FIXME (trask) copy-pasted from ai.java-conventions.gradle
   dependencyManagement(platform(project(":dependencyManagement")))
 
-  smokeTestImplementation(project(":smoke-tests:framework"))
-
-  smokeTestImplementation("org.junit.jupiter:junit-jupiter-api")
-  smokeTestImplementation("org.junit.jupiter:junit-jupiter-params")
-  smokeTestImplementation("org.junit.jupiter:junit-jupiter-engine")
-  smokeTestImplementation("org.junit.platform:junit-platform-launcher")
-
-  smokeTestImplementation("org.assertj:assertj-core")
-
   agent(project(":agent:agent", configuration = "shadow"))
 
   old3xAgent("com.microsoft.azure:applicationinsights-agent:3.2.11")
 }
 
+// Configure test suites
+testing {
+  suites {
+    val test by getting(JvmTestSuite::class)
+
+    register<JvmTestSuite>("smokeTest") {
+      dependencies {
+        implementation(project(":smoke-tests:framework"))
+        
+        implementation("org.junit.jupiter:junit-jupiter-api")
+        implementation("org.junit.jupiter:junit-jupiter-params")
+        runtimeOnly("org.junit.jupiter:junit-jupiter-engine")
+        runtimeOnly("org.junit.platform:junit-platform-launcher")
+
+        implementation("org.assertj:assertj-core")
+      }
+
+      targets {
+        all {
+          testTask.configure {
+            useJUnitPlatform()
+
+            // this is just to force building the agent first
+            dependsOn(":agent:agent:shadowJar")
+
+            shouldRunAfter(test)
+
+            // TODO (trask) experiment with parallelization
+            // maxParallelForks = (Runtime.getRuntime().availableProcessors() / 2).takeIf { it > 0 } ?: 1
+
+            doFirst {
+              val appFile = aiSmokeTest.testAppArtifactDir.file(aiSmokeTest.testAppArtifactFilename.get()).get()
+              val javaagentFile = agent.singleFile
+              val old3xJavaagentFile = old3xAgent.singleFile
+
+              // need to delay for project to configure the extension
+              systemProperty("ai.smoke-test.test-app-file", appFile)
+              systemProperty("ai.smoke-test.javaagent-file", javaagentFile)
+              systemProperty("ai.smoke-test.old-3x-javaagent-file", old3xJavaagentFile)
+
+              val smokeTestMatrix = findProperty("smokeTestMatrix") ?: System.getenv("CI") != null
+              systemProperty("ai.smoke-test.matrix", smokeTestMatrix)
+
+              findProperty("smokeTestRemoteDebug")?.let { systemProperty("ai.smoke-test.remote-debug", it) }
+
+              systemProperty("io.opentelemetry.context.enableStrictContext", true)
+              systemProperty("io.opentelemetry.javaagent.shaded.io.opentelemetry.context.enableStrictContext", true)
+            }
+
+            testLogging {
+              showStandardStreams = true
+              exceptionFormat = TestExceptionFormat.FULL
+            }
+
+            // TODO (trask) this is still a problem
+            //  e.g. changes in agent-tooling do not cause smoke tests to re-run
+            outputs.upToDateWhen { false }
+          }
+        }
+      }
+    }
+  }
+}
+
 configurations.all {
   // spring boot 2.x requires slf4j 1.x
   val slf4jVersion = "1.7.36"
@@ -105,48 +147,4 @@ tasks {
       addStringOption("Xwerror", "-quiet")
     }
   }
-
-  register<Test>("smokeTest") {
-    useJUnitPlatform()
-
-    // this is just to force building the agent first
-    dependsOn(":agent:agent:shadowJar")
-
-    dependsOn(assemble)
-
-    testClassesDirs = sourceSets["smokeTest"].output.classesDirs
-    classpath = sourceSets["smokeTest"].runtimeClasspath
-
-    // TODO (trask) experiment with parallelization
-    // maxParallelForks = (Runtime.getRuntime().availableProcessors() / 2).takeIf { it > 0 } ?: 1
-
-    doFirst {
-
-      val appFile = aiSmokeTest.testAppArtifactDir.file(aiSmokeTest.testAppArtifactFilename.get()).get()
-      val javaagentFile = agent.singleFile
-      val old3xJavaagentFile = old3xAgent.singleFile
-
-      // need to delay for project to configure the extension
-      systemProperty("ai.smoke-test.test-app-file", appFile)
-      systemProperty("ai.smoke-test.javaagent-file", javaagentFile)
-      systemProperty("ai.smoke-test.old-3x-javaagent-file", old3xJavaagentFile)
-
-      val smokeTestMatrix = findProperty("smokeTestMatrix") ?: System.getenv("CI") != null
-      systemProperty("ai.smoke-test.matrix", smokeTestMatrix)
-
-      findProperty("smokeTestRemoteDebug")?.let { systemProperty("ai.smoke-test.remote-debug", it) }
-
-      systemProperty("io.opentelemetry.context.enableStrictContext", true)
-      systemProperty("io.opentelemetry.javaagent.shaded.io.opentelemetry.context.enableStrictContext", true)
-    }
-
-    testLogging {
-      showStandardStreams = true
-      exceptionFormat = TestExceptionFormat.FULL
-    }
-
-    // TODO (trask) this is still a problem
-    //  e.g. changes in agent-tooling do not cause smoke tests to re-run
-    outputs.upToDateWhen { false }
-  }
 }