Prevent Logback from accidentally being used in Log4J2LoggingSystemTests

Update `Log4J2LoggingSystemTests` to exclude Logback and include
'log4j-slf4j-impl'. The `ModifiedClassPathClassLoader` has also been
updated so that it no longer automatically excludes `log4j` artifacts,
instead we now use `@ClassPathExclusions` on the relevant tests.

Fixes gh-19365

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/Log4J2MetricsWithLog4jLoggerContextAutoConfigurationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * 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.
@@ -23,6 +23,7 @@ import org.junit.jupiter.api.Test;
 import org.springframework.boot.actuate.autoconfigure.metrics.test.MetricsRun;
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.boot.testsupport.classpath.ClassPathExclusions;
 import org.springframework.boot.testsupport.classpath.ClassPathOverrides;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -34,6 +35,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Andy Wilkinson
  */
+@ClassPathExclusions("log4j-to-slf4j-*.jar")
 @ClassPathOverrides("org.apache.logging.log4j:log4j-core:2.11.1")
 class Log4J2MetricsWithLog4jLoggerContextAutoConfigurationTests {
 

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/MetricsAutoConfigurationWithLog4j2AndLogbackTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * 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.
@@ -21,6 +21,7 @@ import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.boot.testsupport.classpath.ClassPathExclusions;
 import org.springframework.boot.testsupport.classpath.ClassPathOverrides;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -31,6 +32,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Andy Wilkinson
  */
+@ClassPathExclusions("log4j-to-slf4j-*.jar")
 @ClassPathOverrides({ "org.apache.logging.log4j:log4j-core:2.9.0", "org.apache.logging.log4j:log4j-slf4j-impl:2.9.0" })
 class MetricsAutoConfigurationWithLog4j2AndLogbackTests {
 

spring-boot-project/spring-boot-tools/spring-boot-test-support/src/main/java/org/springframework/boot/testsupport/classpath/ModifiedClassPathClassLoader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * 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.
@@ -242,11 +242,8 @@ final class ModifiedClassPathClassLoader extends URLClassLoader {
 		private final AntPathMatcher matcher = new AntPathMatcher();
 
 		private ClassPathEntryFilter(MergedAnnotation<ClassPathExclusions> annotation) {
-			this.exclusions = new ArrayList<>();
-			this.exclusions.add("log4j-*.jar");
-			if (annotation.isPresent()) {
-				this.exclusions.addAll(Arrays.asList(annotation.getStringArray(MergedAnnotation.VALUE)));
-			}
+			this.exclusions = annotation.getValue(MergedAnnotation.VALUE, String[].class).map(Arrays::asList)
+					.orElse(Collections.emptyList());
 		}
 
 		private boolean isExcluded(URL url) {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/LogbackAndLog4J2ExcludedLoggingSystemTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * 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.
@@ -28,8 +28,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Andy Wilkinson
  */
-// Log4j2 is implicitly excluded due to LOG4J-2030
-@ClassPathExclusions("logback-*.jar")
+@ClassPathExclusions({ "log4j-*.jar", "logback-*.jar" })
 class LogbackAndLog4J2ExcludedLoggingSystemTests {
 
 	@Test

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/Log4J2LoggingSystemTests.java

@@ -40,7 +40,6 @@ import org.apache.logging.log4j.core.util.ShutdownCallbackRegistry;
 import org.apache.logging.log4j.util.PropertiesUtil;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 
@@ -50,6 +49,8 @@ import org.springframework.boot.logging.LoggerConfiguration;
 import org.springframework.boot.logging.LoggingInitializationContext;
 import org.springframework.boot.logging.LoggingSystem;
 import org.springframework.boot.logging.LoggingSystemProperties;
+import org.springframework.boot.testsupport.classpath.ClassPathExclusions;
+import org.springframework.boot.testsupport.classpath.ClassPathOverrides;
 import org.springframework.boot.testsupport.system.CapturedOutput;
 import org.springframework.boot.testsupport.system.OutputCaptureExtension;
 import org.springframework.mock.env.MockEnvironment;
@@ -74,6 +75,8 @@ import static org.mockito.Mockito.times;
  * @author Madhura Bhave
  */
 @ExtendWith(OutputCaptureExtension.class)
+@ClassPathExclusions("logback-*.jar")
+@ClassPathOverrides("org.apache.logging.log4j:log4j-slf4j-impl:2.17.2")
 class Log4J2LoggingSystemTests extends AbstractLoggingSystemTests {
 
 	private final TestLog4J2LoggingSystem loggingSystem = new TestLog4J2LoggingSystem();
@@ -247,11 +250,12 @@ class Log4J2LoggingSystemTests extends AbstractLoggingSystemTests {
 	}
 
 	@Test
-	@Disabled("Uses Logback unintentionally")
 	void loggingThatUsesJulIsCaptured(CapturedOutput output) {
+		String name = getClass().getName();
 		this.loggingSystem.beforeInitialize();
 		this.loggingSystem.initialize(this.initializationContext, null, null);
-		java.util.logging.Logger julLogger = java.util.logging.Logger.getLogger(getClass().getName());
+		this.loggingSystem.setLogLevel(name, LogLevel.TRACE);
+		java.util.logging.Logger julLogger = java.util.logging.Logger.getLogger(name);
 		julLogger.setLevel(java.util.logging.Level.INFO);
 		julLogger.severe("Hello world");
 		assertThat(output).contains("Hello world");