Fix testClassDirs deprecation warning with Gradle 8.1+

Closes gh-23

Author: wilkinsona

src/main/java/io/spring/gradle/compatibilitytest/CompatibilityTestPlugin.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2024 the original author or authors.
+ * Copyright 2014-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -112,6 +112,7 @@ private void configureMatrixTestTask(Project project, Test compatibilityTest, Ja
 			.eachDependency((details) -> dependencyVersions.stream()
 				.filter((dependencyVersion) -> matches(dependencyVersion, details))
 				.forEach((dependencyVersion) -> details.useVersion(dependencyVersion.getVersion())));
+		compatibilityTest.setTestClassesDirs(testSourceSet.getOutput().getClassesDirs());
 		compatibilityTest.setClasspath(
 				project.files(javaCompile.getDestinationDirectory(), testSourceSet.getOutput().getResourcesDir(),
 						sourceSets.getByName(SourceSet.MAIN_SOURCE_SET_NAME).getOutput(), configuration));

src/test/java/io/spring/gradle/compatibilitytest/CompatibilityTestPluginIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2024 the original author or authors.
+ * Copyright 2014-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,12 +16,17 @@
 
 package io.spring.gradle.compatibilitytest;
 
-import org.gradle.testkit.runner.BuildResult;
-import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.extension.ExtendWith;
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.PrintWriter;
 
 import io.spring.gradle.compatibilitytest.testkit.GradleBuild;
 import io.spring.gradle.compatibilitytest.testkit.GradleBuildExtension;
+import org.gradle.testkit.runner.BuildResult;
+import org.gradle.testkit.runner.TaskOutcome;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -117,4 +122,30 @@ void javaCompileTaskIsCreatedForEachPermutation() {
 				"compileCompatibilityTestJava_spring_framework_5.3.1");
 	}
 
+	@Test
+	void testsAreExecutedWithoutDeprecationWarnings() throws IOException {
+		File projectDir = this.gradleBuild.getProjectDir();
+		File exampleTests = new File(projectDir, "src/test/java/example/ExampleTests.java");
+		exampleTests.getParentFile().mkdirs();
+		try (PrintWriter writer = new PrintWriter(new FileWriter(exampleTests))) {
+			writer.println("package example;");
+			writer.println("");
+			writer.println("import org.junit.jupiter.api.Test;");
+			writer.println("");
+			writer.println("class ExampleTests {");
+			writer.println("");
+			writer.println("    @Test");
+			writer.println("    void test() {");
+			writer.println("    }");
+			writer.println("");
+			writer.println("}");
+		}
+		BuildResult result = this.gradleBuild.gradleVersion("8.1").build("build");
+		assertThat(result.task(":compatibilityTest_spring_framework_5.3.0").getOutcome())
+			.isEqualTo(TaskOutcome.SUCCESS);
+		assertThat(result.task(":compatibilityTest_spring_framework_5.3.1").getOutcome())
+			.isEqualTo(TaskOutcome.SUCCESS);
+		assertThat(result.getOutput()).doesNotContain("deprecated");
+	}
+
 }

src/test/java/io/spring/gradle/compatibilitytest/testkit/GradleBuild.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -40,6 +40,8 @@ public class GradleBuild {
 
 	private String script;
 
+	private String gradleVersion;
+
 	void before() throws IOException {
 		this.projectDir = Files.createTempDirectory("gradle-").toFile();
 	}
@@ -67,6 +69,11 @@ public GradleBuild script(String script) {
 		return this;
 	}
 
+	public GradleBuild gradleVersion(String gradleVersion) {
+		this.gradleVersion = gradleVersion;
+		return this;
+	}
+
 	public BuildResult build(String... arguments) {
 		try {
 			return prepareRunner(arguments).build();
@@ -81,10 +88,12 @@ public GradleRunner prepareRunner(String... arguments) throws IOException {
 				StandardCopyOption.REPLACE_EXISTING);
 		GradleRunner gradleRunner = GradleRunner.create()
 			.withProjectDir(this.projectDir)
-			.withPluginClasspath(pluginClasspath());
-		gradleRunner.withDebug(true);
+			.withPluginClasspath(pluginClasspath())
+			.withDebug(true);
+		if (this.gradleVersion != null) {
+			gradleRunner = gradleRunner.withGradleVersion(this.gradleVersion);
+		}
 		List<String> allArguments = new ArrayList<>();
-		allArguments.add("--stacktrace");
 		allArguments.addAll(Arrays.asList(arguments));
 		allArguments.add("--warning-mode");
 		allArguments.add("all");

src/test/resources/io/spring/gradle/compatibilitytest/CompatibilityTestPluginIntegrationTests-testsAreExecutedWithoutDeprecationWarnings.gradle

@@ -0,0 +1,30 @@
+plugins {
+	id 'io.spring.compatibility-test'
+	id 'java'
+}
+
+repositories {
+	mavenCentral()
+}
+
+compatibilityTest {
+	dependency('Spring Framework') { springFramework ->
+		springFramework.groupId = 'org.springframework'
+		springFramework.versions = [
+			'5.3.0',
+			'5.3.1'
+		]
+	}
+}
+
+dependencies {
+	implementation 'org.springframework:spring-core:5.2.10.RELEASE'
+	
+	testImplementation 'org.junit.jupiter:junit-jupiter:5.13.0'
+	
+	testRuntimeOnly 'org.junit.platform:junit-platform-launcher:1.13.0'
+}
+
+tasks.withType(Test).configureEach {
+	useJUnitPlatform();
+}