Continue failure analysis when an analyzer throws an exception

Previously, if a failure analyzer threw an exception from its
analyze method, failure analysis would stop.

This commit updates FailureAnalyzers to catch and log any Throwable
thrown by an analyzer and continue to the next available analyzer.

Closes gh-7956

spring-boot/src/main/java/org/springframework/boot/diagnostics/FailureAnalyzers.java

@@ -115,9 +115,14 @@ public final class FailureAnalyzers {
 
 	private FailureAnalysis analyze(Throwable failure, List<FailureAnalyzer> analyzers) {
 		for (FailureAnalyzer analyzer : analyzers) {
-			FailureAnalysis analysis = analyzer.analyze(failure);
-			if (analysis != null) {
-				return analysis;
+			try {
+				FailureAnalysis analysis = analyzer.analyze(failure);
+				if (analysis != null) {
+					return analysis;
+				}
+			}
+			catch (Throwable ex) {
+				log.debug("FailureAnalyzer " + analyzer + " failed", ex);
 			}
 		}
 		return null;

spring-boot/src/test/java/org/springframework/boot/diagnostics/FailureAnalyzersTests.java

@@ -62,9 +62,16 @@ public class FailureAnalyzersTests {
 	}
 
 	@Test
-	public void brokenAnalyzerDoesNotPreventOtherAnalyzersFromBeingCalled() {
+	public void analyzerThatFailsDuringInitializationDoesNotPreventOtherAnalyzersFromBeingCalled() {
 		RuntimeException failure = new RuntimeException();
-		analyzeAndReport("broken.factories", failure);
+		analyzeAndReport("broken-initialization.factories", failure);
+		verify(failureAnalyzer, times(1)).analyze(failure);
+	}
+
+	@Test
+	public void analyzerThatFailsDuringAnalysisDoesNotPreventOtherAnalyzersFromBeingCalled() {
+		RuntimeException failure = new RuntimeException();
+		analyzeAndReport("broken-analysis.factories", failure);
 		verify(failureAnalyzer, times(1)).analyze(failure);
 	}
 
@@ -83,7 +90,7 @@ public class FailureAnalyzersTests {
 
 	}
 
-	static class BrokenFailureAnalyzer implements FailureAnalyzer {
+	static class BrokenInitializationFailureAnalyzer implements FailureAnalyzer {
 
 		static {
 			Object foo = null;
@@ -97,6 +104,15 @@ public class FailureAnalyzersTests {
 
 	}
 
+	static class BrokenAnalysisFailureAnalyzer implements FailureAnalyzer {
+
+		@Override
+		public FailureAnalysis analyze(Throwable failure) {
+			throw new NoClassDefFoundError();
+		}
+
+	}
+
 	interface BeanFactoryAwareFailureAnalyzer extends BeanFactoryAware, FailureAnalyzer {
 
 	}

spring-boot/src/test/resources/failure-analyzers-tests/broken-analysis.factories

@@ -1,4 +1,4 @@
 # Failure Analyzers
 org.springframework.boot.diagnostics.FailureAnalyzer=\
-org.springframework.boot.diagnostics.FailureAnalyzersTests$BrokenFailureAnalyzer,\
+org.springframework.boot.diagnostics.FailureAnalyzersTests$BrokenAnalysisFailureAnalyzer,\
 org.springframework.boot.diagnostics.FailureAnalyzersTests$BasicFailureAnalyzer

spring-boot/src/test/resources/failure-analyzers-tests/broken-initialization.factories

@@ -0,0 +1,4 @@
+# Failure Analyzers
+org.springframework.boot.diagnostics.FailureAnalyzer=\
+org.springframework.boot.diagnostics.FailureAnalyzersTests$BrokenAnalysisFailureAnalyzer,\
+org.springframework.boot.diagnostics.FailureAnalyzersTests$BasicFailureAnalyzer