Add Log4j2 smoke test

This commit adds a smoke test that exercises the SpringProfile extension
just like the Logback equivalent.

Closes gh-48492

Author: snicoll

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-log4j2/build.gradle

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2012-present 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.
+ */
+
+plugins {
+	id "java"
+}
+
+description = "Spring Boot Log4j2 smoke test"
+
+dependencies {
+	modules {
+		module("org.springframework.boot:spring-boot-starter-logging") {
+			replacedBy("org.springframework.boot:spring-boot-starter-log4j2", "Use Log4j2 instead of Logback")
+		}
+	}
+
+	implementation(project(":spring-boot-project:spring-boot-starters:spring-boot-starter"))
+	implementation(project(":spring-boot-project:spring-boot-starters:spring-boot-starter-log4j2"))
+
+	testImplementation(project(":spring-boot-project:spring-boot-starters:spring-boot-starter-test"))
+}

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-log4j2/src/main/java/smoketest/log4j2/SampleLog4j2Application.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2012-present 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 smoketest.log4j2;
+
+import jakarta.annotation.PostConstruct;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class SampleLog4j2Application {
+
+	private static final Logger logger = LoggerFactory.getLogger(SampleLog4j2Application.class);
+
+	@PostConstruct
+	public void logSomething() {
+		logger.debug("Sample Debug Message");
+		logger.trace("Sample Trace Message");
+	}
+
+	public static void main(String[] args) {
+		SpringApplication.run(SampleLog4j2Application.class, args).close();
+	}
+
+}

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-log4j2/src/main/resources/application.properties

@@ -0,0 +1 @@
+logging.log4j2.config.override=classpath:org/springframework/boot/logging/log4j2/log4j2.xml

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-log4j2/src/main/resources/log4j2-spring.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration status="WARN">
+	<SpringProfile name="staging">
+		<Loggers>
+			<Logger name="smoketest.log4j2" level="TRACE"/>
+			<Root level="INFO">
+				<AppenderRef ref="Console"/>
+			</Root>
+		</Loggers>
+	</SpringProfile>
+	<Loggers>
+		<Logger name="smoketest.log4j2" level="DEBUG"/>
+		<Root level="INFO">
+			<AppenderRef ref="Console"/>
+		</Root>
+	</Loggers>
+</Configuration>

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-log4j2/src/test/java/smoketest/log4j2/SampleLog4j2ApplicationTests.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2012-present 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 smoketest.log4j2;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import org.springframework.boot.test.system.CapturedOutput;
+import org.springframework.boot.test.system.OutputCaptureExtension;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@ExtendWith(OutputCaptureExtension.class)
+class SampleLog4j2ApplicationTests {
+
+	@Test
+	void testLoadedCustomLogbackConfig(CapturedOutput output) {
+		SampleLog4j2Application.main(new String[0]);
+		assertThat(output).contains("Sample Debug Message").doesNotContain("Sample Trace Message");
+	}
+
+	@Test
+	void testProfile(CapturedOutput output) {
+		SampleLog4j2Application.main(new String[] { "--spring.profiles.active=staging" });
+		assertThat(output).contains("Sample Debug Message").contains("Sample Trace Message");
+	}
+
+}

src/checkstyle/checkstyle-suppressions.xml

@@ -44,6 +44,7 @@
 	<suppress files="SpringBootJoranConfiguratorTests\.java" checks="IllegalImport" />
 	<suppress files="LogbackMetricsAutoConfiguration\.java" checks="IllegalImport" />
 	<suppress files="RemoteUrlPropertyExtractorTests\.java" checks="IllegalImport" />
+	<suppress files="SampleLog4j2Application\.java" checks="IllegalImport" />
 	<suppress files="SampleLogbackApplication\.java" checks="IllegalImport" />
 	<suppress files="[\\/]src[\\/]test[\\/]java[\\/]org[\\/]springframework[\\/]boot[\\/]test[\\/]rule[\\/]" checks="SpringJUnit5" />
 	<suppress files="MockBeanWithSpringMethodRuleRepeatJUnit4IntegrationTests" checks="SpringJUnit5" />