prioritize the command handler that is related to command before searching for inheritance fixes: #440 (#441)

Author: osoykan

projects/kediatr-core/src/main/kotlin/com/trendyol/kediatr/RegistryImpl.kt

@@ -8,15 +8,17 @@ class RegistryImpl(
   private val registry = Container(dependencyProvider)
 
   override fun <TCommand : Command> resolveCommandHandler(classOfCommand: Class<TCommand>): CommandHandler<TCommand> {
-    val handler = registry.commandMap[baseClassOrItself(classOfCommand, Command::class.java)]?.get()
+    val handler = registry.commandMap[classOfCommand]?.get()
+      ?: registry.commandMap[baseClassOrItself(classOfCommand, Command::class.java)]?.get()
       ?: throw HandlerNotFoundException("handler could not be found for ${classOfCommand.name}")
     return handler as CommandHandler<TCommand>
   }
 
   override fun <TCommand : CommandWithResult<TResult>, TResult> resolveCommandWithResultHandler(
     classOfCommand: Class<TCommand>
   ): CommandWithResultHandler<TCommand, TResult> {
-    val handler = registry.commandWithResultMap[baseClassOrItself(classOfCommand, CommandWithResult::class.java)]?.get()
+    val handler = registry.commandWithResultMap[classOfCommand]?.get()
+      ?: registry.commandWithResultMap[baseClassOrItself(classOfCommand, CommandWithResult::class.java)]?.get()
       ?: throw HandlerNotFoundException("handler could not be found for ${classOfCommand.name}")
     return handler as CommandWithResultHandler<TCommand, TResult>
   }
@@ -28,7 +30,8 @@ class RegistryImpl(
     .flatMap { (_, v) -> v.map { it.get() as NotificationHandler<TNotification> } }
 
   override fun <TQuery : Query<TResult>, TResult> resolveQueryHandler(classOfQuery: Class<TQuery>): QueryHandler<TQuery, TResult> {
-    val handler = registry.queryMap[baseClassOrItself(classOfQuery, Query::class.java)]?.get()
+    val handler = registry.queryMap[classOfQuery]?.get()
+      ?: registry.queryMap[baseClassOrItself(classOfQuery, Query::class.java)]?.get()
       ?: throw HandlerNotFoundException("handler could not be found for ${classOfQuery.name}")
     return handler as QueryHandler<TQuery, TResult>
   }

projects/kediatr-core/src/test/kotlin/com/trendyol/kediatr/MediatorTests.kt

@@ -41,7 +41,9 @@ class MediatorTests : MediatorUseCases() {
       NotificationHandlerThatPassesThroughOrderedPipelineBehaviours(),
       TestCommandBaseHandler(),
       TestQueryBaseHandler(),
-      TestCommandWithResultBaseHandler()
+      TestCommandWithResultBaseHandler(),
+      TestCommandForInheritanceWithFallbackHandlerHandler(),
+      TestCommandHandlerForCommandInherited2()
     )
   )
 

projects/kediatr-core/src/testFixtures/kotlin/com/trendyol/kediatr/testing/MediatorUseCases.kt

@@ -96,6 +96,19 @@ abstract class MediatorUseCases : MediatorTestConvention() {
     command2.invocationCount() shouldBe 1
   }
 
+  @Test
+  fun inherited_command_with_fallback_gives_priority_to_its_handlers_otherwise_to_fallback_handler() = runTest {
+    val command = TestCommandForInheritanceWithFallback.TestCommandInherited1("id")
+    testMediator.send(command)
+    command.invocationCount() shouldBe 1
+    command.whereItWasInvokedFrom() shouldBe TestCommandForInheritanceWithFallbackHandlerHandler::class.java.name
+
+    val command2 = TestCommandForInheritanceWithFallback.TestCommandInherited2("id")
+    testMediator.send(command2)
+    command2.invocationCount() shouldBe 1
+    command2.whereItWasInvokedFrom() shouldBe TestCommandHandlerForCommandInherited2::class.java.name
+  }
+
   @Test
   fun inherited_query_should_work() = runTest {
     val query = TestQueryBase.TestQueryInherited1("id")

projects/kediatr-core/src/testFixtures/kotlin/com/trendyol/kediatr/testing/models.kt

@@ -17,6 +17,12 @@ abstract class EnrichedWithMetadata {
 
   fun invocationCount(): Int = getMetadata(INVOCATION_COUNT) as? Int ?: 0
 
+  fun whereItWasInvokedFrom(): String = getMetadata("invokedFrom") as? String ?: "unknown"
+
+  fun invokedFrom(nameOfTheHandler: String) {
+    addMetadata("invokedFrom", nameOfTheHandler)
+  }
+
   internal fun visitedPipeline(pipeline: String) {
     val visitedPipelines = visitedPipelines().toMutableSet()
     visitedPipelines.add(pipeline)
@@ -554,3 +560,31 @@ class TestCommandWithResultBaseHandler : CommandWithResultHandler<TestCommandWit
     return "${command.id} handled"
   }
 }
+
+sealed class TestCommandForInheritanceWithFallback :
+  EnrichedWithMetadata(),
+  Command {
+  abstract val id: String
+
+  data class TestCommandInherited1(
+    override val id: String
+  ) : TestCommandForInheritanceWithFallback()
+
+  data class TestCommandInherited2(
+    override val id: String
+  ) : TestCommandForInheritanceWithFallback()
+}
+
+class TestCommandForInheritanceWithFallbackHandlerHandler : CommandHandler<TestCommandForInheritanceWithFallback> {
+  override suspend fun handle(command: TestCommandForInheritanceWithFallback) {
+    command.incrementInvocationCount()
+    command.invokedFrom(javaClass.name)
+  }
+}
+
+class TestCommandHandlerForCommandInherited2 : CommandHandler<TestCommandForInheritanceWithFallback.TestCommandInherited2> {
+  override suspend fun handle(command: TestCommandForInheritanceWithFallback.TestCommandInherited2) {
+    command.incrementInvocationCount()
+    command.invokedFrom(javaClass.name)
+  }
+}

projects/kediatr-koin-starter/src/test/kotlin/com/trendyol/kediatr/koin/MediatorTests.kt

@@ -55,6 +55,8 @@ class MediatorTests :
         single { TestCommandBaseHandler() } bind CommandHandler::class
         single { TestQueryBaseHandler() } bind QueryHandler::class
         single { TestCommandWithResultBaseHandler() } bind CommandWithResultHandler::class
+        single { TestCommandForInheritanceWithFallbackHandlerHandler() } bind CommandHandler::class
+        single { TestCommandHandlerForCommandInherited2() } bind CommandHandler::class
 
         // Extra
         single<MediatorAccessor> { { get<Mediator>() } }

projects/kediatr-quarkus-starter/src/test/kotlin/com/trendyol/kediatr/quarkus/MediatorTests.kt

@@ -117,4 +117,10 @@ class MediatorTests : MediatorUseCases() {
 
   @Produces
   fun handler28() = TestCommandWithResultBaseHandler()
+
+  @Produces
+  fun handler29() = TestCommandForInheritanceWithFallbackHandlerHandler()
+
+  @Produces
+  fun handler30() = TestCommandHandlerForCommandInherited2()
 }

projects/kediatr-spring-boot-2x-starter/src/test/kotlin/com/trendyol/kediatr/spring/MediatorTests.kt

@@ -44,7 +44,9 @@ import org.springframework.context.annotation.*
     NotificationHandlerThatPassesThroughOrderedPipelineBehaviours::class,
     TestCommandBaseHandler::class,
     TestQueryBaseHandler::class,
-    TestCommandWithResultBaseHandler::class
+    TestCommandWithResultBaseHandler::class,
+    TestCommandForInheritanceWithFallbackHandlerHandler::class,
+    TestCommandHandlerForCommandInherited2::class
   ]
 )
 class MediatorTests : MediatorUseCases() {

projects/kediatr-spring-boot-3x-starter/src/test/kotlin/com/trendyol/kediatr/spring/MediatorTests.kt

@@ -44,7 +44,9 @@ import org.springframework.context.annotation.*
     NotificationHandlerThatPassesThroughOrderedPipelineBehaviours::class,
     TestCommandBaseHandler::class,
     TestQueryBaseHandler::class,
-    TestCommandWithResultBaseHandler::class
+    TestCommandWithResultBaseHandler::class,
+    TestCommandForInheritanceWithFallbackHandlerHandler::class,
+    TestCommandHandlerForCommandInherited2::class
   ]
 )
 class MediatorTests : MediatorUseCases() {