Added tests for batch message handler registering.

Author: Anton Vorontsov

src/RabbitMQ.Client.Core.DependencyInjection/BatchMessageHandlerDependencyInjectionExtensions.cs

@@ -24,7 +24,7 @@ public static class BatchMessageHandlerDependencyInjectionExtensions
         public static IServiceCollection AddBatchMessageHandler<TBatchMessageHandler>(this IServiceCollection services, IConfiguration configuration)
             where TBatchMessageHandler : BaseBatchMessageHandler
         {
-            services.CheckIfBatchMessageHandlerAlreadyConfigured<TBatchMessageHandler>();
+            CheckIfBatchMessageHandlerAlreadyConfigured<TBatchMessageHandler>(services);
             var configurationInstance = RabbitMqClientOptionsDependencyInjectionExtensions.GetRabbitMqClientOptionsInstance(configuration);
             services.ConfigureBatchConsumerConnectionOptions<TBatchMessageHandler>(configurationInstance);
             services.AddHostedService<TBatchMessageHandler>();
@@ -41,7 +41,7 @@ public static IServiceCollection AddBatchMessageHandler<TBatchMessageHandler>(th
         public static IServiceCollection AddBatchMessageHandler<TBatchMessageHandler>(this IServiceCollection services, RabbitMqClientOptions configuration)
             where TBatchMessageHandler : BaseBatchMessageHandler
         {
-            services.CheckIfBatchMessageHandlerAlreadyConfigured<TBatchMessageHandler>();
+            CheckIfBatchMessageHandlerAlreadyConfigured<TBatchMessageHandler>(services);
             services.ConfigureBatchConsumerConnectionOptions<TBatchMessageHandler>(configuration);
             services.AddHostedService<TBatchMessageHandler>();
             return services;
@@ -60,14 +60,13 @@ static IServiceCollection ConfigureBatchConsumerConnectionOptions<TBatchMessageH
             return services;
         }
 
-        static IServiceCollection CheckIfBatchMessageHandlerAlreadyConfigured<TBatchMessageHandler>(this IServiceCollection services)
+        static void CheckIfBatchMessageHandlerAlreadyConfigured<TBatchMessageHandler>(this IServiceCollection services)
         {
-            var descriptor = services.FirstOrDefault(x => x.ServiceType == typeof(TBatchMessageHandler));
+            var descriptor = services.FirstOrDefault(x => x.ImplementationType == typeof(TBatchMessageHandler));
             if (descriptor != null)
             {
                 throw new BatchMessageHandlerAlreadyConfiguredException(typeof(TBatchMessageHandler), $"A batch message handler of type {typeof(TBatchMessageHandler)} has already been configured.");
             }
-            return services;
         }
     }
 }

tests/RabbitMQ.Client.Core.DependencyInjection.Tests/UnitTests/BatchMessageHandlerDependencyInjectionExtensionsTests.cs

@@ -0,0 +1,52 @@
+using System.Threading.Tasks;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Moq;
+using RabbitMQ.Client.Core.DependencyInjection.Configuration;
+using RabbitMQ.Client.Core.DependencyInjection.Exceptions;
+using RabbitMQ.Client.Core.DependencyInjection.Tests.UnitTests.Stubs;
+using Xunit;
+
+namespace RabbitMQ.Client.Core.DependencyInjection.Tests.UnitTests
+{
+    public class BatchMessageHandlerDependencyInjectionExtensionsTests
+    {
+        [Fact]
+        public async Task ShouldProperlyThrowExceptionWhenRegisteringSameBatchMessageHandlerTwiceWithConfiguration()
+        {
+            await Assert.ThrowsAsync<BatchMessageHandlerAlreadyConfiguredException>(() =>
+            {
+                var configurationMock = new Mock<IConfiguration>();
+                new ServiceCollection()
+                    .AddBatchMessageHandler<StubBatchMessageHandler>(configurationMock.Object)
+                    .AddBatchMessageHandler<StubBatchMessageHandler>(configurationMock.Object);
+                return Task.CompletedTask;
+            });
+        }
+        
+        [Fact]
+        public async Task ShouldProperlyThrowExceptionWhenRegisteringSameBatchMessageHandlerTwiceWithOptions()
+        {
+            await Assert.ThrowsAsync<BatchMessageHandlerAlreadyConfiguredException>(() =>
+            {
+                new ServiceCollection()
+                    .AddBatchMessageHandler<StubBatchMessageHandler>(new RabbitMqClientOptions())
+                    .AddBatchMessageHandler<StubBatchMessageHandler>(new RabbitMqClientOptions());
+                return Task.CompletedTask;
+            });
+        }
+        
+        [Fact]
+        public async Task ShouldProperlyThrowExceptionWhenRegisteringSameBatchMessageHandlerTwiceWithConfigurationAndOptions()
+        {
+            await Assert.ThrowsAsync<BatchMessageHandlerAlreadyConfiguredException>(() =>
+            {
+                var configurationMock = new Mock<IConfiguration>();
+                new ServiceCollection()
+                    .AddBatchMessageHandler<StubBatchMessageHandler>(configurationMock.Object)
+                    .AddBatchMessageHandler<StubBatchMessageHandler>(new RabbitMqClientOptions());
+                return Task.CompletedTask;
+            });
+        }
+    }
+}

tests/RabbitMQ.Client.Core.DependencyInjection.Tests/UnitTests/Stubs/StubBatchMessageHandler.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using RabbitMQ.Client.Core.DependencyInjection.BatchMessageHandlers;
+using RabbitMQ.Client.Core.DependencyInjection.Models;
+
+namespace RabbitMQ.Client.Core.DependencyInjection.Tests.UnitTests.Stubs
+{
+    public class StubBatchMessageHandler : BaseBatchMessageHandler
+    {
+        readonly ILogger<StubBatchMessageHandler> _logger;
+        
+        public StubBatchMessageHandler(
+            IEnumerable<BatchConsumerConnectionOptions> batchConsumerConnectionOptions,
+            ILogger<StubBatchMessageHandler> logger)
+            : base(batchConsumerConnectionOptions, logger)
+        {
+            _logger = logger;
+        }
+        
+        protected override ushort PrefetchCount { get; set; } = 3;
+        
+        protected override string QueueName { get; set; } = "queue.name";
+        
+        protected override Task HandleMessages(IEnumerable<ReadOnlyMemory<byte>> messages, CancellationToken cancellationToken)
+        {
+            foreach (var message in messages)
+            {
+                var stringifiedMessage = Encoding.UTF8.GetString(message.ToArray());
+                _logger.LogInformation(stringifiedMessage);
+            }
+            return Task.CompletedTask;
+        }
+    }
+}