Conditional registerSingleton to avoid duplication

Author: seregamorph

src/main/java/digital/pragmatech/testing/diagnostic/ContextDiagnosticApplicationInitializer.java

@@ -15,6 +15,8 @@ public class ContextDiagnosticApplicationInitializer
   private static final Logger LOG =
       LoggerFactory.getLogger(ContextDiagnosticApplicationInitializer.class);
 
+  private static final String BEAN_CONTEXT_DIAGNOSTIC = "contextDiagnostic";
+
   @Override
   public void initialize(ConfigurableApplicationContext applicationContext) {
     ContextDiagnostic contextDiagnostic = ContextDiagnostic.started();
@@ -23,9 +25,13 @@ public void initialize(ConfigurableApplicationContext applicationContext) {
         event -> {
           if (event instanceof ContextRefreshedEvent) {
             ContextDiagnostic completedDiagnostic = contextDiagnostic.completed();
-            applicationContext
-                .getBeanFactory()
-                .registerSingleton("contextDiagnostic", completedDiagnostic);
+            // avoid double registration of the same bean when listener was discovered via
+            // spring.factories
+            if (!applicationContext.getBeanFactory().containsSingleton(BEAN_CONTEXT_DIAGNOSTIC)) {
+              applicationContext
+                  .getBeanFactory()
+                  .registerSingleton(BEAN_CONTEXT_DIAGNOSTIC, completedDiagnostic);
+            }
             LOG.debug("Context Diagnostic Completed: {}", completedDiagnostic);
           }
         });