Search implemented interfaces for @ServiceConnection fields

Fixes gh-37671

spring-boot-project/spring-boot-testcontainers/src/main/java/org/springframework/boot/testcontainers/service/connection/ServiceConnectionContextCustomizerFactory.java

@@ -41,6 +41,7 @@ import org.springframework.util.ReflectionUtils;
  * @author Moritz Halbritter
  * @author Andy Wilkinson
  * @author Phillip Webb
+ * @author Scott Frederick
  */
 class ServiceConnectionContextCustomizerFactory implements ContextCustomizerFactory {
 
@@ -61,6 +62,9 @@ class ServiceConnectionContextCustomizerFactory implements ContextCustomizerFact
 		if (TestContextAnnotationUtils.searchEnclosingClass(clazz)) {
 			findSources(clazz.getEnclosingClass(), sources);
 		}
+		for (Class<?> implementedInterface : clazz.getInterfaces()) {
+			findSources(implementedInterface, sources);
+		}
 	}
 
 	@SuppressWarnings("unchecked")

spring-boot-project/spring-boot-testcontainers/src/test/java/org/springframework/boot/testcontainers/service/connection/ServiceConnectionContextCustomizerFactoryTests.java

@@ -71,7 +71,31 @@ class ServiceConnectionContextCustomizerFactoryTests {
 	}
 
 	@Test
-	void createContextCustomizerWhenClassHasNonStaticServiceConnectionFailsWithHepfulException() {
+	void createContextCustomizerWhenInterfaceHasServiceConnectionsReturnsCustomizer() {
+		ServiceConnectionContextCustomizer customizer = (ServiceConnectionContextCustomizer) this.factory
+			.createContextCustomizer(ServiceConnectionsInterface.class, null);
+		assertThat(customizer).isNotNull();
+		assertThat(customizer.getSources()).hasSize(2);
+	}
+
+	@Test
+	void createContextCustomizerWhenSuperclassHasServiceConnectionsReturnsCustomizer() {
+		ServiceConnectionContextCustomizer customizer = (ServiceConnectionContextCustomizer) this.factory
+			.createContextCustomizer(ServiceConnectionsSubclass.class, null);
+		assertThat(customizer).isNotNull();
+		assertThat(customizer.getSources()).hasSize(2);
+	}
+
+	@Test
+	void createContextCustomizerWhenImplementedInterfaceHasServiceConnectionsReturnsCustomizer() {
+		ServiceConnectionContextCustomizer customizer = (ServiceConnectionContextCustomizer) this.factory
+			.createContextCustomizer(ServiceConnectionsImpl.class, null);
+		assertThat(customizer).isNotNull();
+		assertThat(customizer.getSources()).hasSize(2);
+	}
+
+	@Test
+	void createContextCustomizerWhenClassHasNonStaticServiceConnectionFailsWithHelpfulException() {
 		assertThatIllegalStateException()
 			.isThrownBy(() -> this.factory.createContextCustomizer(NonStaticServiceConnection.class, null))
 			.withMessage("@ServiceConnection field 'service' must be static");
@@ -79,7 +103,7 @@ class ServiceConnectionContextCustomizerFactoryTests {
 	}
 
 	@Test
-	void createContextCustomizerWhenClassHasAnnotationOnNonConnectionFieldFailsWithHepfulException() {
+	void createContextCustomizerWhenClassHasAnnotationOnNonConnectionFieldFailsWithHelpfulException() {
 		assertThatIllegalStateException()
 			.isThrownBy(() -> this.factory.createContextCustomizer(ServiceConnectionOnWrongFieldType.class, null))
 			.withMessage("Field 'service2' in " + ServiceConnectionOnWrongFieldType.class.getName()
@@ -141,6 +165,27 @@ class ServiceConnectionContextCustomizerFactoryTests {
 
 	}
 
+	interface ServiceConnectionsInterface {
+
+		@ServiceConnection
+		Container<?> service1 = new MockContainer();
+
+		@ServiceConnection
+		Container<?> service2 = new MockContainer();
+
+		default void dummy() {
+		}
+
+	}
+
+	static class ServiceConnectionsSubclass extends ServiceConnections {
+
+	}
+
+	static class ServiceConnectionsImpl implements ServiceConnectionsInterface {
+
+	}
+
 	static class NonStaticServiceConnection {
 
 		@ServiceConnection