Fix detection of reactive web environments in DevTools

DevToolsPropertyDefaultsPostProcessor looked for
ConfigurableReactiveWebEnvironment
in org.springframework.boot.web.reactive.context by name, but the class
moved to org.springframework.boot.web.context.reactive in 4.0. As a
result, reactive web applications were never identified as web
applications and the hint about setting logging.level.web to DEBUG was
not logged for them.

ConfigurableReactiveWebEnvironment is part of spring-boot, so it is now
referenced directly rather than by name. The servlet environment check
is unchanged as spring-web is an optional dependency.

See gh-51708

Signed-off-by: ohchanKyu <okc0202@naver.com>

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

@@ -28,6 +28,7 @@ import org.springframework.boot.devtools.logger.DevToolsLogFactory;
 import org.springframework.boot.devtools.restart.Restarter;
 import org.springframework.boot.devtools.settings.DevToolsSettings;
 import org.springframework.boot.devtools.system.DevToolsEnablementDeducer;
+import org.springframework.boot.web.context.reactive.ConfigurableReactiveWebEnvironment;
 import org.springframework.core.NativeDetector;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
@@ -55,9 +56,7 @@ 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 String SERVLET_WEB_ENVIRONMENT_CLASS = "org.springframework.web.context.ConfigurableWebEnvironment";
 
 	private static final Map<String, Object> PROPERTIES;
 
@@ -112,13 +111,12 @@ public class DevToolsPropertyDefaultsPostProcessor implements EnvironmentPostPro
 	}
 
 	private boolean isWebApplication(Environment environment) {
-		for (String candidate : WEB_ENVIRONMENT_CLASSES) {
-			Class<?> environmentClass = resolveClassName(candidate, environment.getClass().getClassLoader());
-			if (environmentClass != null && environmentClass.isInstance(environment)) {
-				return true;
-			}
+		if (environment instanceof ConfigurableReactiveWebEnvironment) {
+			return true;
 		}
-		return false;
+		Class<?> servletWebEnvironmentClass = resolveClassName(SERVLET_WEB_ENVIRONMENT_CLASS,
+				environment.getClass().getClassLoader());
+		return servletWebEnvironmentClass != null && servletWebEnvironmentClass.isInstance(environment);
 	}
 
 	private @Nullable Class<?> resolveClassName(String candidate, ClassLoader classLoader) {

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);
+	}
+
+}