Support import of idomatic testcontainer declaration classes

Add an `@ImportTestcontainers` annotation which can be used to import
idomatic testcontainer declaration classes.

Closes gh-35245

spring-boot-project/spring-boot-docs/src/docs/asciidoc/features/testing.adoc

@@ -1062,6 +1062,26 @@ NOTE: Using a `@ServiceConnection` is recommended whenever possible, however, dy
 
 
 
+[[features.testing.testcontainers.at-development-time.importing-container-declarations]]
+===== Importing Testcontainer Declaration Classes
+A common pattern when using Testcontainers is to declare `Container` instances as static fields.
+Often these fields are defined directly on the test class.
+They can also be declared on a parent class or on an interface that the test implements.
+
+For example, the following `MyContainers` interface declares `mongo` and `neo4j` containers:
+
+include::code:MyContainers[]
+
+If you already have containers defined in this way, or you just prefer this style, you can import these declaration classes rather than defining you containers as `@Bean` methods.
+To do so, add the `@ImportTestcontainers` annotation to your test configuration class:
+
+include::code:MyContainersConfiguration[]
+
+TIP: You can use the `@ServiceConnection` annotation on `Container` fields to establish service connections.
+You can also add <<features#features.testing.testcontainers.dynamic-properties,`@DynamicPropertySource` annotated methods>> to your declaration class.
+
+
+
 [[features.testing.utilities]]
 === Test Utilities
 A few test utility classes that are generally useful when testing your application are packaged as part of `spring-boot`.

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/testing/testcontainers/atdevelopmenttime/importingcontainerdeclarations/MyContainers.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2012-2023 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.boot.docs.features.testing.testcontainers.atdevelopmenttime.importingcontainerdeclarations;
+
+import org.testcontainers.containers.MongoDBContainer;
+import org.testcontainers.containers.Neo4jContainer;
+import org.testcontainers.junit.jupiter.Container;
+
+public interface MyContainers {
+
+	@Container
+	MongoDBContainer monogContainer = new MongoDBContainer("mongo:5.0");
+
+	@Container
+	Neo4jContainer<?> neo4jContainer = new Neo4jContainer<>("neo4j:5");
+
+}

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/testing/testcontainers/atdevelopmenttime/importingcontainerdeclarations/MyContainersConfiguration.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2012-2023 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.boot.docs.features.testing.testcontainers.atdevelopmenttime.importingcontainerdeclarations;
+
+import org.springframework.boot.test.context.TestConfiguration;
+import org.springframework.boot.testcontainers.context.ImportTestcontainers;
+
+@TestConfiguration(proxyBeanMethods = false)
+@ImportTestcontainers(MyContainers.class)
+public class MyContainersConfiguration {
+
+}

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/features/testing/testcontainers/atdevelopmenttime/importingcontainerdeclarations/MyContainersConfiguration.kt

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2012-2023 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.boot.docs.features.testing.testcontainers.atdevelopmenttime.importingcontainerdeclarations
+
+import org.springframework.boot.test.context.TestConfiguration
+import org.springframework.boot.testcontainers.context.ImportTestcontainers
+
+@TestConfiguration(proxyBeanMethods = false)
+@ImportTestcontainers(MyContainers::class)
+class MyContainersConfiguration {
+
+}