Merge pull request #2482 from AxonFramework/bug/2481

[#2481] Check `MessageHandlerRegistrar` registration to be non-null
AxonFramework · Nov 28, 2022 · cc2e134 · cc2e134
2 parents 7c187b9 + 2972eb2
commit cc2e134
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Showing 3 changed files with 36 additions and 13 deletions.
diff --git a/config/src/main/java/org/axonframework/config/MessageHandlerRegistrar.java b/config/src/main/java/org/axonframework/config/MessageHandlerRegistrar.java
@@ -19,7 +19,10 @@
 import org.axonframework.common.Registration;
 import org.axonframework.lifecycle.Lifecycle;
 import org.axonframework.lifecycle.Phase;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
+import java.lang.invoke.MethodHandles;
 import java.util.function.BiFunction;
 import java.util.function.Function;
 import java.util.function.Supplier;
@@ -39,6 +42,8 @@
  */
 public class MessageHandlerRegistrar implements Lifecycle {
 
+    private static final Logger logger = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
+
     private final Supplier<Configuration> configurationSupplier;
     private final Function<Configuration, Object> messageHandlerBuilder;
     private final BiFunction<Configuration, Object, Registration> messageHandlerSubscriber;
@@ -90,6 +95,10 @@ public void start() {
      * through the {@link #start()} method.
      */
     public void shutdown() {
+        if (handlerRegistration == null) {
+            logger.info("Shutting down a message handler registrar before it was started.");
+            return;
+        }
         handlerRegistration.cancel();
     }
 }
diff --git a/config/src/test/java/org/axonframework/config/DefaultConfigurerTest.java b/config/src/test/java/org/axonframework/config/DefaultConfigurerTest.java
@@ -705,6 +705,17 @@ void registeringUpcastersReturnsUpcasterChainOverRulingRegisteredUpcasterChainCo
         verifyNoInteractions(testUpcasterChain);
     }
 
+    @Test
+    void shuttingDownTheConfigurationBeforeItStartedWithConfiguredMessageHandlersDoesNotCauseAnyExceptions() {
+        Configuration configuration = DefaultConfigurer.defaultConfiguration()
+                                                       .registerCommandHandler(c -> new Object())
+                                                       .registerEventHandler(c -> new Object())
+                                                       .registerQueryHandler(c -> new Object())
+                                                       .registerMessageHandler(c -> new Object())
+                                                       .buildConfiguration();
+        assertDoesNotThrow(configuration::shutdown);
+    }
+
     @SuppressWarnings("unused")
     @Entity(name = "StubAggregate")
     private static class StubAggregate {

diff --git a/config/src/test/java/org/axonframework/config/MessageHandlerRegistrarTest.java b/config/src/test/java/org/axonframework/config/MessageHandlerRegistrarTest.java
@@ -65,36 +65,39 @@ void startRegistersCreatedMessageHandler(@Mock Configuration config) {
         assertTrue(isRegistered.get());
     }
 
-    /**
-     * The thrown {@link NullPointerException} will always be wrapped in a {@link org.axonframework.lifecycle.LifecycleHandlerInvocationException}
-     * since the {@link MessageHandlerRegistrar#shutdown()} will be wrapped in a {@link LifecycleHandler}.
-     */
     @Test
-    void shutdownThrowsNullPointerExceptionIfRegistrationDidNotHappen(@Mock Configuration config) {
+    void shutdownCancelsMessageHandlerRegistration(@Mock Configuration config) {
+        AtomicBoolean isCanceled = new AtomicBoolean(false);
+
         MessageHandlerRegistrar testSubject = new MessageHandlerRegistrar(
                 () -> config, c -> new SomeMessageHandler(),
-                (c, msgHandler) -> TEST_REGISTRATION_IMPLEMENTATION
+                (c, msgHandler) -> () -> {
+                    isCanceled.set(true);
+                    return false;
+                }
         );
+        testSubject.start();
 
-        assertThrows(NullPointerException.class, testSubject::shutdown);
+        testSubject.shutdown();
+
+        assertTrue(isCanceled.get());
     }
 
     @Test
-    void shutdownCancelsMessageHandlerRegistration(@Mock Configuration config) {
+    void shutdownDoesNotThrowExceptionsIfWhenTheRegistrarHasNotStartedYet(@Mock Configuration config) {
         AtomicBoolean isCanceled = new AtomicBoolean(false);
 
         MessageHandlerRegistrar testSubject = new MessageHandlerRegistrar(
-                () -> config, c -> new SomeMessageHandler(),
+                () -> config,
+                c -> new SomeMessageHandler(),
                 (c, msgHandler) -> () -> {
                     isCanceled.set(true);
                     return false;
                 }
         );
-        testSubject.start();
-
-        testSubject.shutdown();
 
-        assertTrue(isCanceled.get());
+        assertDoesNotThrow(testSubject::shutdown);
+        assertFalse(isCanceled.get());
     }
 
     private static class SomeMessageHandler {