Hotfix: Throw if no assemblies are provided

Author: joel-jeremy

Src/Xer.Cqrs.Extensions.Autofac/ContainerBuilderExtensions.cs

@@ -1,4 +1,5 @@
-using System.Reflection;
+using System;
+using System.Reflection;
 using Xer.Cqrs.Extensions.Autofac;
 
 namespace Autofac
@@ -7,6 +8,21 @@ public static class ContainerBuilderExtensions
     {
         public static ContainerBuilder RegisterCqrs(this ContainerBuilder builder, params Assembly[] assemblies)
         {
+            if (builder == null)
+            {
+                throw new ArgumentNullException(nameof(builder));
+            }
+
+            if (assemblies == null)
+            {
+                throw new ArgumentNullException(nameof(assemblies));
+            }
+
+            if (assemblies.Length == 0)
+            {
+                throw new ArgumentException("No assemblies were provided.", nameof(assemblies));
+            }
+
             builder.RegisterCqrsCore()
                 .RegisterEventHandlers(select => 
                     select.ByInterface(assemblies)
@@ -20,6 +36,11 @@ public static ContainerBuilder RegisterCqrs(this ContainerBuilder builder, param
 
         public static ICqrsBuilder RegisterCqrsCore(this ContainerBuilder builder)
         {
+            if (builder == null)
+            {
+                throw new ArgumentNullException(nameof(builder));
+            }
+
             return new CqrsBuilder(builder);
         }
     }

Src/Xer.Cqrs.Extensions.Autofac/CqrsBuilder.cs

@@ -46,7 +46,7 @@ public ICqrsBuilder RegisterCommandHandlers(Action<ICqrsCommandHandlerSelector>
                         : new CommandDelegator(handlers[0]);
                 }
 
-                return new CommandDelegator(new SingleMessageHandlerRegistration().BuildMessageHandlerResolver());
+                return new CommandDelegator(NullMessageHandlerDelegateResolver.Instance);
             }).As<CommandDelegator>().SingleInstance();
 
             return this;
@@ -73,7 +73,7 @@ public ICqrsBuilder RegisterEventHandlers(Action<ICqrsEventHandlerSelector> sele
                         : new EventDelegator(handlers[0]);
                 }
 
-                return new EventDelegator(new MultiMessageHandlerRegistration().BuildMessageHandlerResolver());
+                return new EventDelegator(NullMessageHandlerDelegateResolver.Instance);
             }).As<EventDelegator>().SingleInstance();
 
             return this;

Src/Xer.Cqrs.Extensions.Autofac/CqrsCommandHandlerSelector.cs

@@ -34,14 +34,16 @@ public ICqrsCommandHandlerSelector ByInterface(Lifetime lifetime, params Assembl
 
             if (assemblies.Length == 0)
             {
-                throw new ArgumentException("No assemblies were provided.", nameof(assemblies));
+                throw new ArgumentException("No command handler assemblies were provided.", nameof(assemblies));
             }
+            
+            Assembly[] distinctAssemblies = assemblies.Distinct().ToArray();
 
-            var asyncHandlerRegistration = _builder.RegisterAssemblyTypes(assemblies.ToArray())
+            var asyncHandlerRegistration = _builder.RegisterAssemblyTypes(distinctAssemblies)
                 .AsClosedTypesOf(typeof(ICommandAsyncHandler<>))
                 .AsImplementedInterfaces();
 
-            var syncHandlerRegistration = _builder.RegisterAssemblyTypes(assemblies.ToArray())
+            var syncHandlerRegistration = _builder.RegisterAssemblyTypes(distinctAssemblies)
                 .AsClosedTypesOf(typeof(ICommandHandler<>))
                 .AsImplementedInterfaces();
 
@@ -87,10 +89,12 @@ public ICqrsCommandHandlerSelector ByAttribute(Lifetime lifetime, params Assembl
 
             if (assemblies.Length == 0)
             {
-                throw new ArgumentException("No assemblies were provided.", nameof(assemblies));
+                throw new ArgumentException("No command handler assemblies were provided.", nameof(assemblies));
             }
+            
+            Assembly[] distinctAssemblies = assemblies.Distinct().ToArray();
 
-            var handlerRegistration = _builder.RegisterAssemblyTypes(assemblies.ToArray())
+            var handlerRegistration = _builder.RegisterAssemblyTypes(distinctAssemblies)
                 .Where(type => type.IsClass && !type.IsAbstract &&
                                CommandHandlerAttributeMethod.IsFoundInType(type))
                 .AsSelf();
@@ -113,7 +117,7 @@ public ICqrsCommandHandlerSelector ByAttribute(Lifetime lifetime, params Assembl
             _builder.Register(context =>
             {
                 SingleMessageHandlerRegistration singleMessageHandlerRegistration = new SingleMessageHandlerRegistration();
-                singleMessageHandlerRegistration.RegisterCommandHandlersByAttribute(assemblies, context.Resolve);
+                singleMessageHandlerRegistration.RegisterCommandHandlersByAttribute(distinctAssemblies, context.Resolve);
                 return new CommandHandlerDelegateResolver(singleMessageHandlerRegistration.BuildMessageHandlerResolver());
             }).AsSelf().SingleInstance();
 

Src/Xer.Cqrs.Extensions.Autofac/CqrsEventHandlerSelector.cs

@@ -1,5 +1,6 @@
 using Autofac;
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
 using Xer.Cqrs.EventStack;
@@ -34,14 +35,16 @@ public ICqrsEventHandlerSelector ByInterface(Lifetime lifetime, params Assembly[
 
             if (assemblies.Length == 0)
             {
-                throw new ArgumentException("No assemblies were provided.", nameof(assemblies));
+                throw new ArgumentException("No event handler assemblies were provided.", nameof(assemblies));
             }
 
-            var asyncHandlerRegistration = _builder.RegisterAssemblyTypes(assemblies.ToArray())
+            Assembly[] distinctAssemblies = assemblies.Distinct().ToArray();
+
+            var asyncHandlerRegistration = _builder.RegisterAssemblyTypes(distinctAssemblies)
                 .AsClosedTypesOf(typeof(IEventAsyncHandler<>))
                 .AsImplementedInterfaces();
 
-            var syncHandlerRegistration = _builder.RegisterAssemblyTypes(assemblies.ToArray())
+            var syncHandlerRegistration = _builder.RegisterAssemblyTypes(distinctAssemblies)
                 .AsClosedTypesOf(typeof(IEventHandler<>))
                 .AsImplementedInterfaces();
 
@@ -84,10 +87,12 @@ public ICqrsEventHandlerSelector ByAttribute(Lifetime lifetime, params Assembly[
 
             if (assemblies.Length == 0)
             {
-                throw new ArgumentException("No assemblies were provided.", nameof(assemblies));
+                throw new ArgumentException("No event handler assemblies were provided.", nameof(assemblies));
             }
 
-            var attributeHandlerRegistration = _builder.RegisterAssemblyTypes(assemblies.ToArray())
+            Assembly[] distinctAssemblies = assemblies.Distinct().ToArray();
+
+            var attributeHandlerRegistration = _builder.RegisterAssemblyTypes(distinctAssemblies)
                 .Where(type => type.IsClass && !type.IsAbstract &&
                                EventHandlerAttributeMethod.IsFoundInType(type))
                 .AsSelf();
@@ -110,7 +115,7 @@ public ICqrsEventHandlerSelector ByAttribute(Lifetime lifetime, params Assembly[
             _builder.Register(context =>
             {
                 var handlerRegistration = new MultiMessageHandlerRegistration();
-                handlerRegistration.RegisterEventHandlersByAttribute(assemblies, context.Resolve);
+                handlerRegistration.RegisterEventHandlersByAttribute(distinctAssemblies, context.Resolve);
                 return new EventHandlerDelegateResolver(handlerRegistration.BuildMessageHandlerResolver());
             }).AsSelf().SingleInstance();
 

Src/Xer.Cqrs.Extensions.Autofac/NullMessageHandlerDelegateResolver.cs

@@ -0,0 +1,16 @@
+using System;
+using Xer.Delegator;
+
+namespace Xer.Cqrs.Extensions.Autofac
+{
+    internal class NullMessageHandlerDelegateResolver : IMessageHandlerResolver
+    {
+        private static readonly Lazy<NullMessageHandlerDelegateResolver> _singleton = new Lazy<NullMessageHandlerDelegateResolver>(() => new NullMessageHandlerDelegateResolver());
+
+        public static readonly NullMessageHandlerDelegateResolver Instance = _singleton.Value;
+
+        private NullMessageHandlerDelegateResolver() { }
+
+        public MessageHandlerDelegate ResolveMessageHandler(Type messageType) => NullMessageHandlerDelegate.Instance;
+    }
+}

Src/Xer.Cqrs.Extensions.Autofac/Xer.Cqrs.Extensions.Autofac.csproj

@@ -2,6 +2,12 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+    <Authors>jeyjeyemem;mvput;xerprojects-contributors;</Authors>
+    <Description>Autofac container integration for Xer.Cqrs</Description>
+    <Copyright>Copyright (c) XerProjects contributors</Copyright>
+    <PackageLicenseUrl>https://github.com/XerProjects/Xer.Cqrs.Extensions.Autofac/blob/dev/LICENSE</PackageLicenseUrl>
+    <PackageProjectUrl>https://github.com/XerProjects/Xer.Cqrs.Extensions.Autofac</PackageProjectUrl>
+    <PackageTags>container;ioc;ioc-container;cqrs;extension;autofac</PackageTags>
   </PropertyGroup>
 
   <ItemGroup>
@@ -11,7 +17,6 @@
     <PackageReference Include="Xer.Cqrs.CommandStack.Extensions.Attributes" Version="1.0.0" />
     <PackageReference Include="Xer.Cqrs.EventStack" Version="2.0.0" />
     <PackageReference Include="Xer.Cqrs.EventStack.Extensions.Attributes" Version="1.0.0" />
-    <PackageReference Include="Xer.Delegator" Version="1.0.0" />
   </ItemGroup>
 
 </Project>