Document how to structure configurations for efficient slice tests

Closes gh-16088

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/howto/testing/slicetests/MyConfiguration.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2012-2022 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.howto.testing.slicetests;
+
+import org.apache.commons.dbcp2.BasicDataSource;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.boot.jdbc.DataSourceBuilder;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.web.SecurityFilterChain;
+
+@Configuration(proxyBeanMethods = false)
+public class MyConfiguration {
+
+	@Bean
+	public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
+		http.authorizeRequests().anyRequest().authenticated();
+		return http.build();
+	}
+
+	@Bean
+	@ConfigurationProperties("app.datasource.second")
+	public BasicDataSource secondDataSource() {
+		return DataSourceBuilder.create().type(BasicDataSource.class).build();
+	}
+
+}

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/howto/testing/slicetests/MyDatasourceConfiguration.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2012-2022 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.howto.testing.slicetests;
+
+import org.apache.commons.dbcp2.BasicDataSource;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.boot.jdbc.DataSourceBuilder;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration(proxyBeanMethods = false)
+class MyDatasourceConfiguration {
+
+	@Bean
+	@ConfigurationProperties("app.datasource.second")
+	public BasicDataSource secondDataSource() {
+		return DataSourceBuilder.create().type(BasicDataSource.class).build();
+	}
+
+}

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/howto/testing/slicetests/MySecurityConfiguration.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2012-2022 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.howto.testing.slicetests;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.web.SecurityFilterChain;
+
+@Configuration(proxyBeanMethods = false)
+class MySecurityConfiguration {
+
+	@Bean
+	public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
+		http.authorizeRequests().anyRequest().authenticated();
+		return http.build();
+	}
+
+}