refactor: share Muzzle report test setup

Author: bric3

buildSrc/src/test/kotlin/datadog/gradle/plugin/muzzle/MuzzlePluginTestFixture.kt

@@ -41,6 +41,30 @@ open class MuzzlePluginTestFixture : GradleFixture() {
     addSubproject("dd-java-agent:instrumentation:demo", instrumentationBuildScript)
   }
 
+  /** Writes an aggregation project with optional instrumentation report producers. */
+  fun writeAggregationProject(vararg producers: String) {
+    addSubproject("dd-java-agent:instrumentation",
+      """
+      plugins {
+        id("java")
+        id("dd-trace-java.muzzle-report-aggregation")
+      }
+      layout.buildDirectory.set(layout.projectDirectory.dir("relocated/build"))
+      muzzleReports.reportFile.set(layout.buildDirectory.file("muzzle-deps-results/dd-java-agent_instrumentation.csv"))
+      dependencies {
+        ${producers.joinToString("\n") { "implementation(project(\":dd-java-agent:instrumentation:$it\"))" }}
+      }
+      tasks.register("muzzleInstrumentationReport") { dependsOn(tasks.named("aggregateMuzzleReports")) }
+      """
+    )
+    writeRootProject(
+      """
+      plugins { id("dd-trace-java.muzzle-report-aggregation") apply false }
+      layout.buildDirectory.set(layout.projectDirectory.dir("relocated/build"))
+      """
+    )
+  }
+
   /**
    * Writes a muzzle scan plugin that always passes.
    */

buildSrc/src/test/kotlin/datadog/gradle/plugin/muzzle/MuzzleReportAggregationTest.kt

@@ -391,28 +391,6 @@ class MuzzleReportAggregationTest : MuzzlePluginTestFixture() {
     )
   }
 
-  private fun writeAggregationProject() {
-    addSubproject("dd-java-agent:instrumentation",
-      """
-      plugins {
-        id("java")
-        id("dd-trace-java.muzzle-report-aggregation")
-      }
-      layout.buildDirectory.set(layout.projectDirectory.dir("relocated/build"))
-      muzzleReports {
-        reportFile.set(layout.buildDirectory.file("muzzle-deps-results/dd-java-agent_instrumentation.csv"))
-      }
-      tasks.register("muzzleInstrumentationReport") { dependsOn(tasks.named("aggregateMuzzleReports")) }
-      """
-    )
-    writeRootProject(
-      """
-      plugins { id("dd-trace-java.muzzle-report-aggregation") apply false }
-      layout.buildDirectory.set(layout.projectDirectory.dir("relocated/build"))
-      """
-    )
-  }
-
   private fun addAggregationInput(projectPath: String, script: String) {
     addSubproject(projectPath, script)
     writeFile("dd-java-agent/instrumentation/build.gradle.kts",

buildSrc/src/test/kotlin/datadog/gradle/plugin/muzzle/MuzzleReportConfigurationCacheTest.kt

@@ -271,22 +271,6 @@ class MuzzleReportConfigurationCacheTest : MuzzlePluginTestFixture() {
     assertThat(reused.output).contains("Reusing configuration cache")
   }
 
-  private fun writeAggregationProject(vararg producers: String) {
-    writeFile("dd-java-agent/instrumentation/build.gradle.kts",
-      """
-      plugins {
-        id("java")
-        id("dd-trace-java.muzzle-report-aggregation")
-      }
-      layout.buildDirectory.set(layout.projectDirectory.dir("relocated/build"))
-      muzzleReports.reportFile.set(layout.buildDirectory.file("muzzle-deps-results/dd-java-agent_instrumentation.csv"))
-      dependencies {
-        ${producers.joinToString("\n") { "implementation(project(\":dd-java-agent:instrumentation:$it\"))" }}
-      }
-      """
-    )
-  }
-
   // Model local report producers without Maven so mutations test the aggregation pipeline alone.
   private val reportProducerScript = """
     import org.gradle.api.attributes.Category