Relax requirements for NoUniqueBeanDefinitionFailureAnalyzer

This commit relaxes the requirements for a non-null description to
handle a NoUniqueBeanDefinitionException. This can happen if the
exception has been thrown programmatically and no injection point
is available.

This allows the programmatic exception thrown when multiple cache
managers are found to be handled properly.

Closes gh-13348

Author: snicoll

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -44,15 +44,13 @@ class NoUniqueBeanDefinitionFailureAnalyzer extends AbstractInjectionFailureAnal
 	@Override
 	protected FailureAnalysis analyze(Throwable rootFailure, NoUniqueBeanDefinitionException cause,
 			String description) {
-		if (description == null) {
-			return null;
-		}
 		String[] beanNames = extractBeanNames(cause);
 		if (beanNames == null) {
 			return null;
 		}
 		StringBuilder message = new StringBuilder();
-		message.append(String.format("%s required a single bean, but %d were found:%n", description, beanNames.length));
+		message.append(String.format("%s required a single bean, but %d were found:%n",
+				(description != null) ? description : "A component", beanNames.length));
 		for (String beanName : beanNames) {
 			buildMessage(message, beanName);
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -19,6 +19,7 @@
 import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.BeanCreationException;
+import org.springframework.beans.factory.NoUniqueBeanDefinitionException;
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.diagnostics.FailureAnalysis;
@@ -101,6 +102,21 @@ void failureAnalysisIncludesPossiblyMissingParameterNames() {
 		assertFoundBeans(failureAnalysis);
 	}
 
+	@Test
+	void failureAnalysisWithoutInjectionPoints() {
+		this.context.registerBean("beanOne", TestBean.class);
+		this.context.register(DuplicateBeansProducer.class);
+		this.context.refresh();
+		FailureAnalysis failureAnalysis = analyzeFailure(new NoUniqueBeanDefinitionException(TestBean.class, 3,
+				"no TestBeanProvider specified and expected single matching TestBean but found 3: beanOne,beanTwo,xmlBean"));
+		assertThat(failureAnalysis.getDescription())
+			.startsWith("A component required a single bean, but 3 were found:");
+		assertThat(failureAnalysis.getDescription()).contains("beanOne: defined in unknown location");
+		assertThat(failureAnalysis.getDescription())
+			.contains("beanTwo: defined by method 'beanTwo' in " + DuplicateBeansProducer.class.getName());
+		assertThat(failureAnalysis.getDescription()).contains("xmlBean: a programmatically registered singleton");
+	}
+
 	private BeanCreationException createFailure(Class<?> consumer) {
 		this.context.registerBean("beanOne", TestBean.class);
 		this.context.register(DuplicateBeansProducer.class, consumer);
@@ -114,7 +130,7 @@ private BeanCreationException createFailure(Class<?> consumer) {
 		return null;
 	}
 
-	private FailureAnalysis analyzeFailure(BeanCreationException failure) {
+	private FailureAnalysis analyzeFailure(Exception failure) {
 		return this.analyzer.analyze(failure);
 	}