diff --git a/src/Volo.DependencyInjection/Microsoft/Extensions/DependencyInjection/ServiceCollectionConventionalRegistrationExtensions.cs b/src/Volo.DependencyInjection/Microsoft/Extensions/DependencyInjection/ServiceCollectionConventionalRegistrationExtensions.cs
index 409f018b8b..d8066fa21e 100644
--- a/src/Volo.DependencyInjection/Microsoft/Extensions/DependencyInjection/ServiceCollectionConventionalRegistrationExtensions.cs
+++ b/src/Volo.DependencyInjection/Microsoft/Extensions/DependencyInjection/ServiceCollectionConventionalRegistrationExtensions.cs
@@ -3,11 +3,6 @@ using Volo.DependencyInjection;
 
 namespace Microsoft.Extensions.DependencyInjection
 {
-    /* TODO: String IConventionalRegistrar objects in a static Dictionary
-     * may cause a performance problem if we create too many short lived IServiceCollection instances.
-     * Normally, an application will have a single IServiceCollection instance, but we should consider edge cases is there are.
-     */
-
     public static class ServiceCollectionConventionalRegistrationExtensions
     {
         public static IServiceCollection AddConventionalRegistrar(this IServiceCollection services, IConventionalRegistrar registrar)
diff --git a/test/Volo.DependencyInjection.Tests/Microsoft/Extensions/DependencyInjection/AbpConventionalDependencyInjectionExtensions_Tests.cs b/test/Volo.DependencyInjection.Tests/Microsoft/Extensions/DependencyInjection/AbpConventionalDependencyInjectionExtensions_Tests.cs
index c9e4126838..367757b8f8 100644
--- a/test/Volo.DependencyInjection.Tests/Microsoft/Extensions/DependencyInjection/AbpConventionalDependencyInjectionExtensions_Tests.cs
+++ b/test/Volo.DependencyInjection.Tests/Microsoft/Extensions/DependencyInjection/AbpConventionalDependencyInjectionExtensions_Tests.cs
@@ -5,9 +5,6 @@ using Xunit;
 
 namespace Microsoft.Extensions.DependencyInjection
 {
-    //TODO: Add unit test for:
-    // - IConventionalRegistrar
-
     public class AbpConventionalDependencyInjectionExtensions_Tests
     {
         private readonly IServiceCollection _services;
diff --git a/test/Volo.DependencyInjection.Tests/Volo/DependencyInjection/ConventionalRegistrar_Test.cs b/test/Volo.DependencyInjection.Tests/Volo/DependencyInjection/ConventionalRegistrar_Test.cs
new file mode 100644
index 0000000000..ee20014d76
--- /dev/null
+++ b/test/Volo.DependencyInjection.Tests/Volo/DependencyInjection/ConventionalRegistrar_Test.cs
@@ -0,0 +1,49 @@
+using System;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Volo.DependencyInjection
+{
+    public class ConventionalRegistrar_Tests
+    {
+        public void Should_Use_Custom_Conventions_If_Added()
+        {
+            //Arrange
+            var services = new ServiceCollection();
+
+            //Act
+            services.AddConventionalRegistrar(new MyCustomConventionalRegistrar());
+            services.AddTypes(typeof(MyCustomClass), typeof(MyClass), typeof(MyNonRegisteredClass));
+
+            //Assert
+            services.ShouldContainTransient(typeof(MyClass)); //Registered by default convention.
+            services.ShouldContainSingleton(typeof(MyCustomClass)); //Registered by custom convention.
+            services.ShouldNotContainService(typeof(MyNonRegisteredClass)); //Not registered by any convention.
+        }
+
+        public class MyCustomConventionalRegistrar : ConventionalRegistrarBase
+        {
+            public override void AddType(IServiceCollection services, Type type)
+            {
+                if (type == typeof(MyClass))
+                {
+                    services.AddSingleton<MyCustomClass>();
+                }
+            }
+        }
+
+        public class MyCustomClass
+        {
+            
+        }
+
+        public class MyNonRegisteredClass
+        {
+
+        }
+
+        public class MyClass : ITransientDependency
+        {
+            
+        }
+    }
+}