Improve failure analysis action when circular references are allowed

Closes gh-27735

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/diagnostics/analyzer/BeanCurrentlyInCreationFailureAnalyzer.java

@@ -19,10 +19,14 @@ package org.springframework.boot.diagnostics.analyzer;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanCreationException;
 import org.springframework.beans.factory.BeanCurrentlyInCreationException;
+import org.springframework.beans.factory.BeanFactory;
+import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.beans.factory.InjectionPoint;
 import org.springframework.beans.factory.UnsatisfiedDependencyException;
+import org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory;
 import org.springframework.boot.diagnostics.AbstractFailureAnalyzer;
 import org.springframework.boot.diagnostics.FailureAnalysis;
 import org.springframework.util.StringUtils;
@@ -33,7 +37,17 @@ import org.springframework.util.StringUtils;
  *
  * @author Andy Wilkinson
  */
-class BeanCurrentlyInCreationFailureAnalyzer extends AbstractFailureAnalyzer<BeanCurrentlyInCreationException> {
+class BeanCurrentlyInCreationFailureAnalyzer extends AbstractFailureAnalyzer<BeanCurrentlyInCreationException>
+		implements BeanFactoryAware {
+
+	private AbstractAutowireCapableBeanFactory beanFactory;
+
+	@Override
+	public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
+		if (beanFactory instanceof AbstractAutowireCapableBeanFactory) {
+			this.beanFactory = (AbstractAutowireCapableBeanFactory) beanFactory;
+		}
+	}
 
 	@Override
 	protected FailureAnalysis analyze(Throwable rootFailure, BeanCurrentlyInCreationException cause) {
@@ -41,12 +55,18 @@ class BeanCurrentlyInCreationFailureAnalyzer extends AbstractFailureAnalyzer<Bea
 		if (dependencyCycle == null) {
 			return null;
 		}
-		return new FailureAnalysis(buildMessage(dependencyCycle),
+		return new FailureAnalysis(buildMessage(dependencyCycle), action(), cause);
-				"Relying upon circular references is discouraged and they are prohibited by default. "
+	}
+
+	private String action() {
+		if (this.beanFactory != null && this.beanFactory.isAllowCircularReferences()) {
+			return "Despite circular references being allowed, the dependency cycle between beans could not be "
+					+ "broken. Update your application to remove the dependency cycle.";
+		}
+		return "Relying upon circular references is discouraged and they are prohibited by default. "
 				+ "Update your application to remove the dependency cycle between beans. "
 				+ "As a last resort, it may be possible to break the cycle automatically by setting "
-						+ "spring.main.allow-circular-references to true if you have not already done so.",
+				+ "spring.main.allow-circular-references to true.";
-				cause);
 	}
 
 	private DependencyCycle findCycle(Throwable rootFailure) {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/diagnostics/analyzer/BeanCurrentlyInCreationFailureAnalyzerTests.java

@@ -26,13 +26,12 @@ import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.BeanCurrentlyInCreationException;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory;
 import org.springframework.boot.diagnostics.FailureAnalysis;
-import org.springframework.boot.diagnostics.FailureAnalyzer;
 import org.springframework.boot.diagnostics.analyzer.BeanCurrentlyInCreationFailureAnalyzerTests.CycleWithAutowiredFields.BeanThreeConfiguration;
 import org.springframework.boot.diagnostics.analyzer.BeanCurrentlyInCreationFailureAnalyzerTests.CycleWithAutowiredFields.BeanTwoConfiguration;
 import org.springframework.boot.diagnostics.analyzer.BeanCurrentlyInCreationFailureAnalyzerTests.CyclicBeanMethodsConfiguration.InnerConfiguration;
 import org.springframework.boot.diagnostics.analyzer.BeanCurrentlyInCreationFailureAnalyzerTests.CyclicBeanMethodsConfiguration.InnerConfiguration.InnerInnerConfiguration;
-import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -47,7 +46,7 @@ import static org.junit.jupiter.api.Assertions.fail;
  */
 class BeanCurrentlyInCreationFailureAnalyzerTests {
 
-	private final FailureAnalyzer analyzer = new BeanCurrentlyInCreationFailureAnalyzer();
+	private final BeanCurrentlyInCreationFailureAnalyzer analyzer = new BeanCurrentlyInCreationFailureAnalyzer();
 
 	@Test
 	void cyclicBeanMethods() throws IOException {
@@ -131,6 +130,18 @@ class BeanCurrentlyInCreationFailureAnalyzerTests {
 		assertThat(this.analyzer.analyze(new BeanCurrentlyInCreationException("test"))).isNull();
 	}
 
+	@Test
+	void cycleWithCircularReferencesAllowed() throws IOException {
+		FailureAnalysis analysis = performAnalysis(CyclicBeanMethodsConfiguration.class, true);
+		assertThat(analysis.getAction()).contains("Despite circular references being allowed");
+	}
+
+	@Test
+	void cycleWithCircularReferencesProhibited() throws IOException {
+		FailureAnalysis analysis = performAnalysis(CyclicBeanMethodsConfiguration.class, false);
+		assertThat(analysis.getAction()).contains("As a last resort");
+	}
+
 	private List<String> readDescriptionLines(FailureAnalysis analysis) throws IOException {
 		try (BufferedReader reader = new BufferedReader(new StringReader(analysis.getDescription()))) {
 			return reader.lines().collect(Collectors.toList());
@@ -138,13 +149,23 @@ class BeanCurrentlyInCreationFailureAnalyzerTests {
 	}
 
 	private FailureAnalysis performAnalysis(Class<?> configuration) {
-		FailureAnalysis analysis = this.analyzer.analyze(createFailure(configuration));
+		return performAnalysis(configuration, true);
+	}
+
+	private FailureAnalysis performAnalysis(Class<?> configuration, boolean allowCircularReferences) {
+		FailureAnalysis analysis = this.analyzer.analyze(createFailure(configuration, allowCircularReferences));
 		assertThat(analysis).isNotNull();
 		return analysis;
 	}
 
-	private Exception createFailure(Class<?> configuration) {
+	private Exception createFailure(Class<?> configuration, boolean allowCircularReferences) {
-		try (ConfigurableApplicationContext context = new AnnotationConfigApplicationContext(configuration)) {
+		try (AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext()) {
+			context.register(configuration);
+			AbstractAutowireCapableBeanFactory beanFactory = (AbstractAutowireCapableBeanFactory) context
+					.getBeanFactory();
+			this.analyzer.setBeanFactory(beanFactory);
+			beanFactory.setAllowCircularReferences(allowCircularReferences);
+			context.refresh();
 			fail("Expected failure did not occur");
 			return null;
 		}