GH-1388 - Fix test resource lookup for Kotlin in Javadoc processing APT.

Co-authored-by: Dennis Wittkötter <dw@logentis.de>

Author: odrotbohm

spring-modulith-apt/src/main/java/org/springframework/modulith/apt/SpringModulithProcessor.java

@@ -134,7 +134,7 @@ public void init(ProcessingEnvironment environment) {
 
 			var path = placeholder.toUri().toString();
 
-			if (path.contains(BuildSystemUtils.getTestTarget())) {
+			if (BuildSystemUtils.pointsToTestTarget(path)) {
 				this.testExecution = true;
 			}
 

spring-modulith-docs/src/main/java/org/springframework/modulith/docs/util/BuildSystemUtils.java

@@ -26,6 +26,7 @@
  * Utilities to detect the build system used.
  *
  * @author Oliver Drotbohm
+ * @author Dennis Wittkötter
  * @since 1.3
  */
 public class BuildSystemUtils {
@@ -57,11 +58,25 @@ public static Optional<Resource> getTargetResource(String path) {
 	 * Returns the path to the folder containing test classes.
 	 *
 	 * @return will never be {@literal null}.
+	 * @deprecated since 1.4.4, 2.0. Use {@link #pointsToTestTarget(String)} instead.
 	 */
+	@Deprecated(since = "1.4.4, 2.0", forRemoval = true)
 	public static String getTestTarget() {
 		return isMaven() ? "target/test-classes" : "build/classes/java/test";
 	}
 
+	/**
+	 * Returns whether the given path points to a resource in the test target folder.
+	 *
+	 * @param path must not be {@literal null} or empty.
+	 */
+	public static boolean pointsToTestTarget(String path) {
+
+		Assert.hasText(path, "Path must not be null or empty!");
+
+		return isMaven() ? pointsToMavenTestTarget(path) : pointsToGradleTestTarget(path);
+	}
+
 	/**
 	 * Returns the path to the target folder for resources.
 	 *
@@ -72,6 +87,14 @@ public static String getResourceTarget() {
 		return isMaven() ? "target/classes" : "build/resources/main";
 	}
 
+	static boolean pointsToMavenTestTarget(String path) {
+		return path.matches("target\\/test-classes\\/.*");
+	}
+
+	static boolean pointsToGradleTestTarget(String path) {
+		return path.matches("build(\\/.+)?\\/classes(\\/(java|kotlin))?\\/(test|testFixtures)\\/.*");
+	}
+
 	private static String getTargetFolder() {
 		return isMaven() ? "target" : "build";
 	}

spring-modulith-docs/src/test/java/org/springframework/modulith/docs/util/BuildSystemUtilsUnitTests.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.modulith.docs.util;
+
+import static org.assertj.core.api.Assertions.*;
+
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.DynamicTest;
+import org.junit.jupiter.api.TestFactory;
+
+/**
+ * Unit tests for {@link BuildSystemUtils}.
+ *
+ * @author Oliver Drotbohm
+ */
+class BuildSystemUtilsUnitTests {
+
+	@TestFactory // GH-1386
+	Stream<DynamicTest> detectsMavenTargetResources() {
+
+		var values = getSampleResources("target/test-classes");
+
+		return DynamicTest.stream(values, it -> it + " is a test resource", it -> {
+			assertThat(BuildSystemUtils.pointsToTestTarget(it)).isTrue();
+		});
+	}
+
+	@TestFactory // GH-1386
+	Stream<DynamicTest> detectsGradleTargetResources() {
+
+		var values = getSampleResources(
+				"build/classes/java/test",
+				"build/classes/kotlin/test",
+				"build/tmp/kapt3/classes/testFixtures");
+
+		return DynamicTest.stream(values, it -> it + " is a test resource", it -> {
+			assertThat(BuildSystemUtils.pointsToGradleTestTarget(it)).isTrue();
+		});
+	}
+
+	private Stream<String> getSampleResources(String... paths) {
+		return Stream.of(paths).map(it -> it.concat("/some-test-resource.txt"));
+	}
+}