Switch @SpringBootTest to UseMainMethod.NEVER by default

See gh-22405

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

@@ -153,25 +153,17 @@ For example, here is an application that changes the banner mode and sets additi
 
 include::code:custom/MyApplication[]
 
-Since customizations in the `main` method can affect the resulting `ApplicationContext`, Spring Boot will also attempt to use the `main` method for tests.
-By default, `@SpringBootTest` will detect any `main` method on your `@SpringBootConfiguration` and run it in order to capture the `ApplicationContext`.
-If your `@SpringBootConfiguration` class doesn't have a main method, the class itself is used directly to create the `ApplicationContext`.
+Since customizations in the `main` method can affect the resulting `ApplicationContext`, it's possible that you might also want to use the `main` method to create the `ApplicationContext` used in your tests.
+By default, `@SpringBootTest` will not call your `main` method, and instead the class itself is used directly to create the `ApplicationContext`
 
-In some situations, you may find that you can't or don't want to run the `main` method in your tests.
-If that's the case, you can change the `useMainMethod` attribute of `@SpringBootTest` to `UseMainMethod.NEVER`.
+If you want to change this behavior, you can change the `useMainMethod` attribute of `@SpringBootTest` to `UseMainMethod.ALWAYS` or `UseMainMethod.WHEN_AVAILABLE`.
+When set to `ALWAYS`, the test will fail if no `main` method can be found.
+When set to `WHEN_AVAILABLE` the `main` method will be used if it is available, otherwise the standard loading mechanism will be used.
 
-For example, you might have the following application class:
+For example, the following test will invoke the `main` method of `MyApplication` in order to create the `ApplicationContext`.
+If the main method sets additional profiles then those will be active when the `ApplicationContext` starts.
 
-include::code:never/MyApplication[]
-
-If a test wants to use the `MyApplication` configuration without calling the main method, it can be written as follows:
-
-include::code:never/MyApplicationTests[]
-
-The test above will still use `MyApplication` to create the `ApplicationContext`, however, it won't call `MyCode.expensiveOperation()` since the `main` method is not invoked.
-
-If you want to do the opposite, and ensure that the `main` method is always invoked, you can set the `useMainMethod` attribute of `@SpringBootTest` to `UseMainMethod.ALWAYS`.
-If this property is set, and no `main` method can be found the test will fail.
+include::code:always/MyApplicationTests[]
 
 
 

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/testing/springbootapplications/usingmain/always/MyApplicationTests.java

@@ -14,14 +14,14 @@
  * limitations under the License.
  */
 
-package org.springframework.boot.docs.features.testing.springbootapplications.usingmain.never;
+package org.springframework.boot.docs.features.testing.springbootapplications.usingmain.always;
 
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.SpringBootTest.UseMainMethod;
 
-@SpringBootTest(useMainMethod = UseMainMethod.NEVER)
+@SpringBootTest(useMainMethod = UseMainMethod.ALWAYS)
 public class MyApplicationTests {
 
 	@Test

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/testing/springbootapplications/usingmain/never/MyApplication.java

@@ -1,30 +0,0 @@
-/*
- * 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.features.testing.springbootapplications.usingmain.never;
-
-import org.springframework.boot.SpringApplication;
-import org.springframework.boot.autoconfigure.SpringBootApplication;
-
-@SpringBootApplication
-public class MyApplication {
-
-	public static void main(String[] args) {
-		MyCode.expensiveOperation();
-		SpringApplication.run(MyApplication.class, args);
-	}
-
-}

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/testing/springbootapplications/usingmain/never/MyCode.java

@@ -1,27 +0,0 @@
-/*
- * 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.features.testing.springbootapplications.usingmain.never;
-
-public final class MyCode {
-
-	private MyCode() {
-	}
-
-	static void expensiveOperation() {
-	}
-
-}

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/features/testing/springbootapplications/usingmain/always/MyApplicationTests.kt

@@ -14,14 +14,14 @@
  * limitations under the License.
  */
 
-package org.springframework.boot.docs.features.testing.springbootapplications.usingmain.custom.never
+package org.springframework.boot.docs.features.testing.springbootapplications.usingmain.custom.always
 
 import org.junit.jupiter.api.Test
 import org.springframework.boot.test.context.SpringBootTest
 import org.springframework.boot.test.context.SpringBootTest.UseMainMethod
 import org.springframework.context.annotation.Import
 
-@SpringBootTest(useMainMethod = UseMainMethod.NEVER)
+@SpringBootTest(useMainMethod = UseMainMethod.ALWAYS)
 class MyApplicationTests {
 
 	@Test

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/features/testing/springbootapplications/usingmain/never/MyApplication.kt

@@ -1,29 +0,0 @@
-/*
- * 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.features.testing.springbootapplications.usingmain.custom.never
-
-import org.springframework.boot.autoconfigure.SpringBootApplication
-import org.springframework.boot.docs.using.structuringyourcode.locatingthemainclass.MyApplication
-import org.springframework.boot.runApplication
-
-@SpringBootApplication
-class MyApplication
-
-fun main(args: Array<String>) {
-	MyCode.expensiveOperation()
-	runApplication<MyApplication>(*args)
-}

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/features/testing/springbootapplications/usingmain/never/MyCode.kt

@@ -1,24 +0,0 @@
-/*
- * 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.features.testing.springbootapplications.usingmain.custom.never
-
-class MyCode {
-	companion object {
-		fun expensiveOperation() {
-		}
-	}
-}

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/SpringBootTest.java

@@ -131,7 +131,7 @@ public @interface SpringBootTest {
 	 * @return the type of main method usage
 	 * @since 3.0.0
 	 */
-	UseMainMethod useMainMethod() default UseMainMethod.WHEN_AVAILABLE;
+	UseMainMethod useMainMethod() default UseMainMethod.NEVER;
 
 	/**
 	 * An enumeration web environment modes.

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/SpringBootTestAnnotation.java

@@ -55,7 +55,7 @@ class SpringBootTestAnnotation implements ContextCustomizer {
 	private SpringBootTestAnnotation(SpringBootTest annotation) {
 		this.args = (annotation != null) ? annotation.args() : NO_ARGS;
 		this.webEnvironment = (annotation != null) ? annotation.webEnvironment() : WebEnvironment.NONE;
-		this.useMainMethod = (annotation != null) ? annotation.useMainMethod() : UseMainMethod.WHEN_AVAILABLE;
+		this.useMainMethod = (annotation != null) ? annotation.useMainMethod() : UseMainMethod.NEVER;
 	}
 
 	@Override

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-data-ldap/src/test/java/smoketest/data/ldap/SampleLdapApplicationTests.java

@@ -20,7 +20,6 @@ import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.boot.test.context.SpringBootTest.UseMainMethod;
 import org.springframework.boot.test.system.CapturedOutput;
 import org.springframework.boot.test.system.OutputCaptureExtension;
 
@@ -32,7 +31,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Phillip Webb
  */
 @ExtendWith(OutputCaptureExtension.class)
-@SpringBootTest(useMainMethod = UseMainMethod.NEVER)
+@SpringBootTest
 class SampleLdapApplicationTests {
 
 	@Test

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-profile/src/test/java/smoketest/profile/ActiveProfilesTests.java

@@ -21,7 +21,6 @@ import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.env.EnvironmentPostProcessor;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.boot.test.context.SpringBootTest.UseMainMethod;
 import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
 import org.springframework.core.env.Environment;
 import org.springframework.test.context.ActiveProfiles;
@@ -34,8 +33,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Madhura Bhave
  */
-@SpringBootTest(useMainMethod = UseMainMethod.NEVER, webEnvironment = WebEnvironment.NONE,
-		properties = { "enableEnvironmentPostProcessor=true" }) // gh-28530
+@SpringBootTest(webEnvironment = WebEnvironment.NONE, properties = { "enableEnvironmentPostProcessor=true" }) // gh-28530
 @ActiveProfiles("hello")
 class ActiveProfilesTests {
 

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-profile/src/test/java/smoketest/profile/AttributeInjectionTests.java

@@ -20,12 +20,11 @@ import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.boot.test.context.SpringBootTest.UseMainMethod;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 // gh-29169
-@SpringBootTest(useMainMethod = UseMainMethod.NEVER, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
 class AttributeInjectionTests {
 
 	@Autowired(required = false)