GH-345 - Properly handle manually declared entity scan and autoconfiguration packages.

If Spring Modulith packages were explicitly configured as autoconfiguration or entity scan packages, the test autoconfiguration would fail as it previously attempted to manipulate an immutable list. We now create a copy of that list to fix this.

spring-modulith-test/src/main/java/org/springframework/modulith/test/ModuleTestAutoConfiguration.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.modulith.test;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
@@ -72,14 +73,15 @@ class ModuleTestAutoConfiguration {
 				return;
 			}
 
+			var packagesToSet = new ArrayList<>(packages);
 			var definition = registry.getBeanDefinition(beanName);
 			var holder = definition.getConstructorArgumentValues().getArgumentValue(0, String[].class);
 
 			Arrays.stream((String[]) holder.getValue())
 					.filter(it -> it.startsWith("org.springframework.modulith"))
-					.forEach(packages::add);
+					.forEach(packagesToSet::add);
 
-			definition.getConstructorArgumentValues().addIndexedArgumentValue(0, packages.toArray(String[]::new));
+			definition.getConstructorArgumentValues().addIndexedArgumentValue(0, packagesToSet.toArray(String[]::new));
 		}
 	}
 }

spring-modulith-test/src/test/java/org/springframework/modulith/test/ModuleTestAutoConfigurationIntegrationTests.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2023 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.test;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.autoconfigure.domain.EntityScan;
+import org.springframework.boot.autoconfigure.domain.EntityScanPackages;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+
+/**
+ * Integration tests for {@link ModuleTestAutoConfiguration}.
+ *
+ * @author Oliver Drotbohm
+ */
+class ModuleTestAutoConfigurationIntegrationTests {
+
+	@Test // GH-345
+	void bootstrapsTestWithManualEntityScanOfModulithPackage() {
+
+		new ApplicationContextRunner()
+				.withBean(ModuleTestExecution.class, ModuleTestExecution.of(ModuleTest.class))
+				.withConfiguration(AutoConfigurations.of(ModuleTestAutoConfiguration.class))
+				.withUserConfiguration(ManualModulithEntityScan.class)
+				.run(ctx -> {
+
+					assertThat(ctx).hasNotFailed();
+					assertThat(ctx.getBean(EntityScanPackages.class).getPackageNames())
+							.containsExactlyInAnyOrder("org.springframework.modulith.test",
+									"org.springframework.modulith.events.jpa");
+				});
+	}
+
+	@SpringBootApplication
+	@ApplicationModuleTest
+	static class ModuleTest {}
+
+	@EnableAutoConfiguration
+	@EntityScan("org.springframework.modulith.events.jpa")
+	static class ManualModulithEntityScan {}
+}