Change state change logging to DEBUG

Update `ApplicationAvailabilityBean` so that state change logging is
at DEBUG rather than INFO.

Fixes gh-26624

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/availability/ApplicationAvailabilityBean.java

@@ -38,10 +38,18 @@ import org.springframework.util.Assert;
 public class ApplicationAvailabilityBean
 		implements ApplicationAvailability, ApplicationListener<AvailabilityChangeEvent<?>> {
 
-	private static final Log logger = LogFactory.getLog(ApplicationAvailabilityBean.class);
-
 	private final Map<Class<? extends AvailabilityState>, AvailabilityChangeEvent<?>> events = new HashMap<>();
 
+	private final Log logger;
+
+	public ApplicationAvailabilityBean() {
+		this(LogFactory.getLog(ApplicationAvailabilityBean.class));
+	}
+
+	ApplicationAvailabilityBean(Log logger) {
+		this.logger = logger;
+	}
+
 	@Override
 	public <S extends AvailabilityState> S getState(Class<S> stateType, S defaultState) {
 		Assert.notNull(stateType, "StateType must not be null");
@@ -65,8 +73,8 @@ public class ApplicationAvailabilityBean
 	@Override
 	public void onApplicationEvent(AvailabilityChangeEvent<?> event) {
 		Class<? extends AvailabilityState> type = getStateType(event.getState());
-		if (logger.isInfoEnabled()) {
-			logger.info(getLogMessage(type, event));
+		if (this.logger.isDebugEnabled()) {
+			this.logger.debug(getLogMessage(type, event));
 		}
 		this.events.put(type, event);
 	}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/availability/ApplicationAvailabilityBeanTests.java

@@ -17,16 +17,22 @@
 package org.springframework.boot.availability;
 
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
 
+import org.apache.commons.logging.Log;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.extension.ExtendWith;
 
-import org.springframework.boot.testsupport.system.CapturedOutput;
-import org.springframework.boot.testsupport.system.OutputCaptureExtension;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.BDDMockito.willAnswer;
+import static org.mockito.Mockito.mock;
 
 /**
  * Tests for {@link ApplicationAvailabilityBean}
@@ -34,17 +40,19 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Brian Clozel
  * @author Phillip Webb
  */
-@ExtendWith(OutputCaptureExtension.class)
 class ApplicationAvailabilityBeanTests {
 
 	private AnnotationConfigApplicationContext context;
 
 	private ApplicationAvailabilityBean availability;
 
+	private MockLog log;
+
 	@BeforeEach
 	void setup() {
-		this.context = new AnnotationConfigApplicationContext(ApplicationAvailabilityBean.class);
+		this.context = new AnnotationConfigApplicationContext(TestConfiguration.class);
 		this.availability = this.context.getBean(ApplicationAvailabilityBean.class);
+		this.log = this.context.getBean(MockLog.class);
 	}
 
 	@Test
@@ -94,27 +102,26 @@ class ApplicationAvailabilityBeanTests {
 	}
 
 	@Test
-	void stateChangesAreLogged(CapturedOutput output) {
+	void stateChangesAreLogged() {
 		AvailabilityChangeEvent.publish(this.context, LivenessState.CORRECT);
-		assertThat(output)
-				.contains("Application availability state LivenessState changed to CORRECT" + System.lineSeparator());
+		assertThat(this.log.getLogged()).contains("Application availability state LivenessState changed to CORRECT");
 		AvailabilityChangeEvent.publish(this.context, LivenessState.BROKEN);
-		assertThat(output).contains(
-				"Application availability state LivenessState changed from CORRECT to BROKEN" + System.lineSeparator());
+		assertThat(this.log.getLogged())
+				.contains("Application availability state LivenessState changed from CORRECT to BROKEN");
 	}
 
 	@Test
-	void stateChangesAreLoggedWithExceptionSource(CapturedOutput output) {
+	void stateChangesAreLoggedWithExceptionSource() {
 		AvailabilityChangeEvent.publish(this.context, new IOException("connection error"), LivenessState.BROKEN);
-		assertThat(output).contains("Application availability state LivenessState changed to BROKEN: "
-				+ "java.io.IOException: connection error" + System.lineSeparator());
+		assertThat(this.log.getLogged()).contains("Application availability state LivenessState changed to BROKEN: "
+				+ "java.io.IOException: connection error");
 	}
 
 	@Test
-	void stateChangesAreLoggedWithOtherSource(CapturedOutput output) {
+	void stateChangesAreLoggedWithOtherSource() {
 		AvailabilityChangeEvent.publish(this.context, new CustomEventSource(), LivenessState.BROKEN);
-		assertThat(output).contains("Application availability state LivenessState changed to BROKEN: "
-				+ CustomEventSource.class.getName() + System.lineSeparator());
+		assertThat(this.log.getLogged()).contains(
+				"Application availability state LivenessState changed to BROKEN: " + CustomEventSource.class.getName());
 	}
 
 	enum TestState implements AvailabilityState {
@@ -141,4 +148,30 @@ class ApplicationAvailabilityBeanTests {
 
 	}
 
+	@Configuration
+	static class TestConfiguration {
+
+		@Bean
+		MockLog mockLog() {
+			List<String> logged = new ArrayList<>();
+			MockLog log = mock(MockLog.class);
+			given(log.isDebugEnabled()).willReturn(true);
+			given(log.getLogged()).willReturn(logged);
+			willAnswer((invocation) -> logged.add("" + invocation.getArguments()[0])).given(log).debug(any());
+			return log;
+		}
+
+		@Bean
+		ApplicationAvailabilityBean applicationAvailabilityBean(MockLog log) {
+			return new ApplicationAvailabilityBean(log);
+		}
+
+	}
+
+	interface MockLog extends Log {
+
+		List<String> getLogged();
+
+	}
+
 }