Add RemoveAll extension method to service collection (#539)

src/Microsoft.Extensions.DependencyInjection.Abstractions/Extensions/ServiceCollectionDescriptorExtensions.cs

@@ -540,5 +540,40 @@ public static IServiceCollection Replace(
             collection.Add(descriptor);
             return collection;
         }
+
+        /// <summary>
+        /// Removes all services of type <typeparamef name="T"/> in <see cref="IServiceCollection"/>.
+        /// </summary>
+        /// <param name="collection">The <see cref="IServiceCollection"/>.</param>
+        /// <returns></returns>
+        public static IServiceCollection RemoveAll<T>(this IServiceCollection collection)
+        {
+            return RemoveAll(collection, typeof(T));
+        }
+
+        /// <summary>
+        /// Removes all services of type <paramef name="serviceType"/> in <see cref="IServiceCollection"/>.
+        /// </summary>
+        /// <param name="collection">The <see cref="IServiceCollection"/>.</param>
+        /// <param name="serviceType">The service type to remove.</param>
+        /// <returns></returns>
+        public static IServiceCollection RemoveAll(this IServiceCollection collection, Type serviceType)
+        {
+            if (serviceType == null)
+            {
+                throw new ArgumentNullException(nameof(serviceType));
+            }
+
+            for (var i = collection.Count - 1; i >= 0; i--)
+            {
+                var descriptor = collection[i];
+                if (descriptor.ServiceType == serviceType)
+                {
+                    collection.RemoveAt(i);
+                }
+            }
+
+            return collection;
+        }
     }
 }

test/Microsoft.Extensions.DependencyInjection.Tests/ServiceCollectionServiceExtensionsTest.cs

@@ -395,5 +395,24 @@ public void Replace_ReplacesFirstServiceWithMatchingServiceType()
             // Assert
             Assert.Equal(new[] { descriptor2, descriptor3 }, collection);
         }
+
+        [Fact]
+        public void RemoveAll_RemovesAllServicesWithMatchingServiceType()
+        {
+            // Arrange
+            var descriptor = new ServiceDescriptor(typeof(IFakeServiceInstance), typeof(FakeService), ServiceLifetime.Transient);
+            var collection = new ServiceCollection
+            {
+                descriptor,
+                new ServiceDescriptor(typeof(IFakeService), typeof(FakeService), ServiceLifetime.Transient),
+                new ServiceDescriptor(typeof(IFakeService), typeof(FakeService), ServiceLifetime.Transient)
+            };
+
+            // Act
+            collection.RemoveAll<IFakeService>();
+
+            // Assert
+            Assert.Equal(new[] { descriptor }, collection);
+        }
     }
 }