Refactor code to merge messages in ChannelMerger to respect the priority without relying on equals based on message name

Author: sam0r040

springwolf-core/src/main/java/io/github/stavshamir/springwolf/asyncapi/MessageHelper.java

@@ -4,10 +4,11 @@
 import io.github.stavshamir.springwolf.asyncapi.types.channel.operation.message.Message;
 import lombok.extern.slf4j.Slf4j;
 
-import java.util.Arrays;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeSet;
@@ -32,7 +33,7 @@ public static Object toMessageObjectOrComposition(Set<Message> messages) {
             case 1:
                 return messages.toArray()[0];
             default:
-                return ImmutableMap.of(ONE_OF, new HashSet<>(messages.stream().collect(Collectors.toCollection(messageSupplier))));
+                return ImmutableMap.of(ONE_OF, new ArrayList<>(messages.stream().collect(Collectors.toCollection(messageSupplier))));
         }
     }
 
@@ -43,12 +44,11 @@ public static Set<Message> messageObjectToSet(Object messageObject) {
         }
 
         if (messageObject instanceof Map) {
-            Set<Message> messages = ((Map<String, Set<Message>>) messageObject).get(ONE_OF);
+            List<Message> messages = ((Map<String, List<Message>>) messageObject).get(ONE_OF);
             return new HashSet<>(messages);
         }
 
         log.warn("Message object must contain either a Message or a Map<String, Set<Message>, but contained: {}", messageObject.getClass());
         return new HashSet<>();
     }
-
 }

springwolf-core/src/main/java/io/github/stavshamir/springwolf/asyncapi/scanners/channels/ChannelMerger.java

@@ -5,7 +5,15 @@
 import io.github.stavshamir.springwolf.asyncapi.MessageHelper;
 import io.github.stavshamir.springwolf.asyncapi.types.channel.operation.message.Message;
 
-import java.util.*;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.TreeSet;
+import java.util.function.Function;
+import java.util.stream.Collectors;
 
 import static io.github.stavshamir.springwolf.asyncapi.MessageHelper.toMessageObjectOrComposition;
 
@@ -42,17 +50,25 @@ public static Map<String, ChannelItem> merge(List<Map.Entry<String, ChannelItem>
     }
 
     private static Operation mergeOperation(Operation operation, Operation otherOperation) {
-        Set<Message> mergedMessages = getMessages(operation);
-        Set<Message> currentEntryMessages = getMessages(otherOperation);
-        mergedMessages.addAll(currentEntryMessages);
-
         Operation mergedOperation = operation != null ? operation : otherOperation;
+
+        Set<Message> mergedMessages = mergeMessages(getMessages(operation), getMessages(otherOperation));
         if (!mergedMessages.isEmpty()) {
             mergedOperation.setMessage(toMessageObjectOrComposition(mergedMessages));
         }
         return mergedOperation;
     }
 
+    private static Set<Message> mergeMessages(Set<Message> messages, Set<Message> otherMessages) {
+        Map<String, Message> nameToMessage = messages.stream().collect(Collectors.toMap(Message::getName, Function.identity()));
+
+        for (Message otherMessage : otherMessages) {
+            nameToMessage.putIfAbsent(otherMessage.getName(), otherMessage);
+        }
+
+        return new HashSet<>(nameToMessage.values());
+    }
+
     private static Set<Message> getMessages(Operation operation) {
         return Optional
                 .ofNullable(operation)

springwolf-core/src/test/java/io/github/stavshamir/springwolf/asyncapi/MessageHelperTest.java

@@ -1,5 +1,6 @@
 package io.github.stavshamir.springwolf.asyncapi;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import io.github.stavshamir.springwolf.asyncapi.types.channel.operation.message.Message;
@@ -50,7 +51,7 @@ public void toMessageObjectOrComposition_multipleMessages() {
 
         assertThat(asObject)
                 .isInstanceOf(Map.class)
-                .isEqualTo(ImmutableMap.of("oneOf", ImmutableSet.of(message1, message2)));
+                .isEqualTo(ImmutableMap.of("oneOf", ImmutableList.of(message2, message1)));
     }
 
     @Test
@@ -75,7 +76,7 @@ public void toMessageObjectOrComposition_multipleMessages_remove_duplicates() {
         // Message3 is not included as it is identical in terms of payload type (Message#name) to message 2
         assertThat(asObject)
                 .isInstanceOf(Map.class)
-                .isEqualTo(ImmutableMap.of("oneOf", ImmutableSet.of(message1, message2)));
+                .isEqualTo(ImmutableMap.of("oneOf", ImmutableList.of(message2, message1)));
     }
 
     @Test

springwolf-core/src/test/java/io/github/stavshamir/springwolf/asyncapi/scanners/channels/ChannelMergerTest.java

@@ -16,7 +16,6 @@
 
 public class ChannelMergerTest {
 
-
     @Test
     public void shouldNotMergeDifferentChannelNames() {
         // given
@@ -110,8 +109,7 @@ public void shouldMergeDifferentMessageForSameOperation() {
 
         // then expectedMessage only includes message1 and message2.
         // Message3 is not included as it is identical in terms of payload type (Message#name) to message 2
-        // TODO Is it really expected that the first occurrence is used? (no test in Message Helper...)
-        Object expectedMessages = MessageHelper.toMessageObjectOrComposition(Sets.newHashSet(message1, message3));
+        Object expectedMessages = MessageHelper.toMessageObjectOrComposition(Sets.newHashSet(message1, message2));
         assertThat(mergedChannels).hasSize(1)
                 .hasEntrySatisfying(channelName, it -> {
                     assertThat(it.getPublish()).isEqualTo(Operation.builder().operationId("publisher1").message(expectedMessages).build());