Merge pull request #51708 from ohchanKyu

Closes gh-51708

* fix-devtools-reactive-web-environment-detection:
  Polish "Fix detection of reactive web environments in DevTools"
  Fix detection of reactive web environments in DevTools

module/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/env/DevToolsPropertyDefaultsPostProcessor.java

@@ -55,9 +55,9 @@ public class DevToolsPropertyDefaultsPostProcessor implements EnvironmentPostPro
 
 	private static final String WEB_LOGGING = "logging.level.web";
 
-	private static final String[] WEB_ENVIRONMENT_CLASSES = {
-			"org.springframework.web.context.ConfigurableWebEnvironment",
-			"org.springframework.boot.web.reactive.context.ConfigurableReactiveWebEnvironment" };
+	private static final WebEnvironmentClassResolver[] WEB_ENVIRONMENT_CLASS_RESOLVERS = new WebEnvironmentClassResolver[] {
+			WebEnvironmentClassResolver.fromClassName("org.springframework.web.context.ConfigurableWebEnvironment"),
+			(classloader) -> org.springframework.boot.web.context.reactive.ConfigurableReactiveWebEnvironment.class };
 
 	private static final Map<String, Object> PROPERTIES;
 
@@ -112,8 +112,9 @@ public class DevToolsPropertyDefaultsPostProcessor implements EnvironmentPostPro
 	}
 
 	private boolean isWebApplication(Environment environment) {
-		for (String candidate : WEB_ENVIRONMENT_CLASSES) {
-			Class<?> environmentClass = resolveClassName(candidate, environment.getClass().getClassLoader());
+		ClassLoader classLoader = environment.getClass().getClassLoader();
+		for (WebEnvironmentClassResolver resolver : WEB_ENVIRONMENT_CLASS_RESOLVERS) {
+			Class<?> environmentClass = resolver.resolve(classLoader);
 			if (environmentClass != null && environmentClass.isInstance(environment)) {
 				return true;
 			}
@@ -121,13 +122,21 @@ public class DevToolsPropertyDefaultsPostProcessor implements EnvironmentPostPro
 		return false;
 	}
 
-	private @Nullable Class<?> resolveClassName(String candidate, ClassLoader classLoader) {
-		try {
-			return ClassUtils.resolveClassName(candidate, classLoader);
-		}
-		catch (IllegalArgumentException ex) {
-			return null;
+	private interface WebEnvironmentClassResolver {
+
+		@Nullable Class<?> resolve(ClassLoader classLoader);
+
+		static WebEnvironmentClassResolver fromClassName(String candidate) {
+			return (classLoader) -> {
+				try {
+					return ClassUtils.resolveClassName(candidate, classLoader);
+				}
+				catch (IllegalArgumentException ex) {
+					return null;
+				}
+			};
 		}
+
 	}
 
 }

module/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/env/DevToolsPropertyDefaultsPostProcessorTests.java

@@ -0,0 +1,87 @@
+/*
+ * 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 org.springframework.boot.devtools.env;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.logging.DeferredLog;
+import org.springframework.boot.test.system.CapturedOutput;
+import org.springframework.boot.test.system.OutputCaptureExtension;
+import org.springframework.boot.test.util.TestPropertyValues;
+import org.springframework.boot.web.context.reactive.StandardReactiveWebEnvironment;
+import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.core.env.StandardEnvironment;
+import org.springframework.test.util.ReflectionTestUtils;
+import org.springframework.web.context.support.StandardServletEnvironment;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link DevToolsPropertyDefaultsPostProcessor}.
+ *
+ * @author ohchanKyu
+ */
+@ExtendWith(OutputCaptureExtension.class)
+class DevToolsPropertyDefaultsPostProcessorTests {
+
+	private static final String WEB_LOGGING_HINT = "For additional web related logging consider setting the "
+			+ "'logging.level.web' property to 'DEBUG'";
+
+	@Test
+	void postProcessWhenServletWebEnvironmentLogsWebLoggingHint(CapturedOutput output) throws Exception {
+		postProcess(new StandardServletEnvironment());
+		assertThat(output).contains(WEB_LOGGING_HINT);
+	}
+
+	@Test
+	void postProcessWhenReactiveWebEnvironmentLogsWebLoggingHint(CapturedOutput output) throws Exception {
+		postProcess(new StandardReactiveWebEnvironment());
+		assertThat(output).contains(WEB_LOGGING_HINT);
+	}
+
+	@Test
+	void postProcessWhenNonWebEnvironmentDoesNotLogWebLoggingHint(CapturedOutput output) throws Exception {
+		postProcess(new StandardEnvironment());
+		assertThat(output).doesNotContain(WEB_LOGGING_HINT);
+	}
+
+	@Test
+	void postProcessWhenWebLoggingIsConfiguredDoesNotLogWebLoggingHint(CapturedOutput output) throws Exception {
+		StandardReactiveWebEnvironment environment = new StandardReactiveWebEnvironment();
+		TestPropertyValues.of("logging.level.web=DEBUG").applyTo(environment);
+		postProcess(environment);
+		assertThat(output).doesNotContain(WEB_LOGGING_HINT);
+	}
+
+	private void postProcess(ConfigurableEnvironment environment) throws Exception {
+		DevToolsPropertyDefaultsPostProcessor postProcessor = new DevToolsPropertyDefaultsPostProcessor();
+		// Run in a new thread so that DevTools is not disabled by the test runner
+		Thread thread = new Thread(() -> postProcessor.postProcessEnvironment(environment, new SpringApplication()));
+		thread.start();
+		thread.join();
+		replayDeferredLog();
+	}
+
+	private void replayDeferredLog() {
+		Object logger = ReflectionTestUtils.getField(DevToolsPropertyDefaultsPostProcessor.class, "logger");
+		assertThat(logger).isInstanceOf(DeferredLog.class);
+		((DeferredLog) logger).switchTo(DevToolsPropertyDefaultsPostProcessor.class);
+	}
+
+}