Add keyed service registration support

src/Scrutor/AttributeSelector.cs

@@ -37,7 +37,9 @@ void ISelector.Populate(IServiceCollection services, RegistrationStrategy? regis
 
                 foreach (var serviceType in serviceTypes)
                 {
-                    var descriptor = new ServiceDescriptor(serviceType, type, attribute.Lifetime);
+                    var descriptor = attribute.ServiceKey is null
+                        ? new ServiceDescriptor(serviceType, type, attribute.Lifetime)
+                        : new ServiceDescriptor(serviceType, attribute.ServiceKey, type, attribute.Lifetime);
 
                     strategy.Apply(services, descriptor);
                 }
@@ -47,6 +49,6 @@ void ISelector.Populate(IServiceCollection services, RegistrationStrategy? regis
 
     private static IEnumerable<ServiceDescriptorAttribute> GetDuplicates(IEnumerable<ServiceDescriptorAttribute> attributes)
     {
-        return attributes.GroupBy(s => s.ServiceType).SelectMany(grp => grp.Skip(1));
+        return attributes.GroupBy(s => new { s.ServiceType, s.ServiceKey }).SelectMany(grp => grp.Skip(1));
     }
 }

src/Scrutor/ServiceDescriptorAttribute.cs

@@ -13,16 +13,21 @@ public ServiceDescriptorAttribute() : this(null) { }
 
     public ServiceDescriptorAttribute(Type? serviceType) : this(serviceType, ServiceLifetime.Transient) { }
 
-    public ServiceDescriptorAttribute(Type? serviceType, ServiceLifetime lifetime)
+    public ServiceDescriptorAttribute(Type? serviceType, ServiceLifetime lifetime) : this(serviceType, lifetime, null) { }
+
+    public ServiceDescriptorAttribute(Type? serviceType, ServiceLifetime lifetime, object? serviceKey)
     {
         ServiceType = serviceType;
         Lifetime = lifetime;
+        ServiceKey = serviceKey;
     }
 
     public Type? ServiceType { get; }
 
     public ServiceLifetime Lifetime { get; }
 
+    public object? ServiceKey { get; }
+
     public IEnumerable<Type> GetServiceTypes(Type fallbackType)
     {
         if (ServiceType is null)
@@ -60,4 +65,8 @@ public sealed class ServiceDescriptorAttribute<TService> : ServiceDescriptorAttr
     public ServiceDescriptorAttribute() : base(typeof(TService)) { }
 
     public ServiceDescriptorAttribute(ServiceLifetime lifetime) : base(typeof(TService), lifetime) { }
+
+    public ServiceDescriptorAttribute(object? serviceKey) : base(typeof(TService), ServiceLifetime.Transient, serviceKey) { }
+
+    public ServiceDescriptorAttribute(ServiceLifetime lifetime, object? serviceKey) : base(typeof(TService), lifetime, serviceKey) { }
 }

test/Scrutor.Tests/KeyedServiceTests.cs

@@ -0,0 +1,329 @@
+using Microsoft.Extensions.DependencyInjection;
+using System;
+using System.Linq;
+using Xunit;
+
+namespace Scrutor.Tests;
+
+public class KeyedServiceTests : TestBase
+{
+    private IServiceCollection Collection { get; } = new ServiceCollection();
+
+    [Fact]
+    public void CanRegisterKeyedServiceWithStringKey()
+    {
+        Collection.Scan(scan => scan
+            .FromTypes(typeof(KeyedTransientService))
+            .UsingAttributes());
+
+        Assert.Single(Collection);
+
+        var service = Collection.Single();
+        Assert.Equal(typeof(IKeyedTestService), service.ServiceType);
+        Assert.Equal(typeof(KeyedTransientService), service.KeyedImplementationType);
+        Assert.Equal("test-key", service.ServiceKey);
+        Assert.Equal(ServiceLifetime.Transient, service.Lifetime);
+        Assert.True(service.IsKeyedService);
+    }
+
+    [Fact]
+    public void CanRegisterKeyedServiceWithGenericAttribute()
+    {
+        Collection.Scan(scan => scan
+            .FromTypes(typeof(GenericKeyedService))
+            .UsingAttributes());
+
+        Assert.Single(Collection);
+
+        var service = Collection.Single();
+        Assert.Equal(typeof(IKeyedTestService), service.ServiceType);
+        Assert.Equal(typeof(GenericKeyedService), service.KeyedImplementationType);
+        Assert.Equal("generic-key", service.ServiceKey);
+        Assert.Equal(ServiceLifetime.Scoped, service.Lifetime);
+        Assert.True(service.IsKeyedService);
+    }
+
+    [Fact]
+    public void CanRegisterMultipleKeyedServicesOnSameType()
+    {
+        Collection.Scan(scan => scan
+            .FromTypes(typeof(MultipleKeyedService))
+            .UsingAttributes());
+
+        Assert.Equal(2, Collection.Count);
+
+        var services = Collection.ToArray();
+
+        var service1 = services.First(s => s.ServiceKey?.ToString() == "key1");
+        Assert.Equal(typeof(IKeyedTestService), service1.ServiceType);
+        Assert.Equal(typeof(MultipleKeyedService), service1.KeyedImplementationType);
+        Assert.Equal(ServiceLifetime.Transient, service1.Lifetime);
+
+        var service2 = services.First(s => s.ServiceKey?.ToString() == "key2");
+        Assert.Equal(typeof(IKeyedTestService), service2.ServiceType);
+        Assert.Equal(typeof(MultipleKeyedService), service2.KeyedImplementationType);
+        Assert.Equal(ServiceLifetime.Singleton, service2.Lifetime);
+    }
+
+    [Fact]
+    public void CanRegisterMixedKeyedAndNonKeyedServices()
+    {
+        Collection.Scan(scan => scan
+            .FromTypes(typeof(MixedKeyedService))
+            .UsingAttributes());
+
+        Assert.Equal(2, Collection.Count);
+
+        var keyedService = Collection.First(s => s.IsKeyedService);
+        Assert.Equal(typeof(IKeyedTestService), keyedService.ServiceType);
+        Assert.Equal(typeof(MixedKeyedService), keyedService.KeyedImplementationType);
+        Assert.Equal("mixed-key", keyedService.ServiceKey);
+        Assert.Equal(ServiceLifetime.Scoped, keyedService.Lifetime);
+
+        var nonKeyedService = Collection.First(s => !s.IsKeyedService);
+        Assert.Equal(typeof(IKeyedTestService), nonKeyedService.ServiceType);
+        Assert.Equal(typeof(MixedKeyedService), nonKeyedService.ImplementationType);
+        Assert.Null(nonKeyedService.ServiceKey);
+        Assert.Equal(ServiceLifetime.Transient, nonKeyedService.Lifetime);
+    }
+
+    [Fact]
+    public void CanResolveKeyedServices()
+    {
+        var provider = ConfigureProvider(services =>
+        {
+            services.Scan(scan => scan
+                .FromTypes(typeof(KeyedTransientService), typeof(GenericKeyedService), typeof(MultipleKeyedService))
+                .UsingAttributes());
+        });
+
+        var keyedTransient = provider.GetRequiredKeyedService<IKeyedTestService>("test-key");
+        Assert.IsType<KeyedTransientService>(keyedTransient);
+
+        using var scope = provider.CreateScope();
+        var genericKeyed = scope.ServiceProvider.GetRequiredKeyedService<IKeyedTestService>("generic-key");
+        Assert.IsType<GenericKeyedService>(genericKeyed);
+
+        var multipleKeyed1 = provider.GetRequiredKeyedService<IKeyedTestService>("key1");
+        Assert.IsType<MultipleKeyedService>(multipleKeyed1);
+
+        var multipleKeyed2 = provider.GetRequiredKeyedService<IKeyedTestService>("key2");
+        Assert.IsType<MultipleKeyedService>(multipleKeyed2);
+
+        // Verify they are different instances for transient services
+        var anotherKeyedTransient = provider.GetRequiredKeyedService<IKeyedTestService>("test-key");
+        Assert.NotSame(keyedTransient, anotherKeyedTransient);
+
+        // Verify singleton behavior
+        var anotherMultipleKeyed2 = provider.GetRequiredKeyedService<IKeyedTestService>("key2");
+        Assert.Same(multipleKeyed2, anotherMultipleKeyed2);
+    }
+
+    [Fact]
+    public void KeyedServicesAreIsolatedFromNonKeyedServices()
+    {
+        var provider = ConfigureProvider(services =>
+        {
+            services.Scan(scan => scan
+                .FromTypes(typeof(MixedKeyedService))
+                .UsingAttributes());
+        });
+
+        using var scope = provider.CreateScope();
+        var keyedService = scope.ServiceProvider.GetRequiredKeyedService<IKeyedTestService>("mixed-key");
+        var nonKeyedService = provider.GetRequiredService<IKeyedTestService>();
+
+        Assert.IsType<MixedKeyedService>(keyedService);
+        Assert.IsType<MixedKeyedService>(nonKeyedService);
+        Assert.NotSame(keyedService, nonKeyedService);
+    }
+
+    [Fact]
+    public void CanRegisterKeyedServiceWithObjectKey()
+    {
+        Collection.Scan(scan => scan
+            .FromTypes(typeof(ObjectKeyedService))
+            .UsingAttributes());
+
+        Assert.Single(Collection);
+
+        var service = Collection.Single();
+        Assert.Equal(typeof(IKeyedTestService), service.ServiceType);
+        Assert.Equal(typeof(ObjectKeyedService), service.KeyedImplementationType);
+        Assert.Equal(42, service.ServiceKey);
+        Assert.True(service.IsKeyedService);
+    }
+
+    [Fact]
+    public void CanResolveKeyedServiceWithObjectKey()
+    {
+        var provider = ConfigureProvider(services =>
+        {
+            services.Scan(scan => scan
+                .FromTypes(typeof(ObjectKeyedService))
+                .UsingAttributes());
+        });
+
+        var keyedService = provider.GetRequiredKeyedService<IKeyedTestService>(42);
+        Assert.IsType<ObjectKeyedService>(keyedService);
+    }
+
+    [Fact]
+    public void CanRegisterKeyedServiceWithEnumKey()
+    {
+        Collection.Scan(scan => scan
+            .FromTypes(typeof(EnumKeyedService))
+            .UsingAttributes());
+
+        Assert.Single(Collection);
+
+        var service = Collection.Single();
+        Assert.Equal(typeof(IKeyedTestService), service.ServiceType);
+        Assert.Equal(typeof(EnumKeyedService), service.KeyedImplementationType);
+        Assert.Equal(TestEnum.Value1, service.ServiceKey);
+        Assert.True(service.IsKeyedService);
+    }
+
+    [Fact]
+    public void CanRegisterKeyedServiceWithDifferentServiceTypes()
+    {
+        Collection.Scan(scan => scan
+            .FromTypes(typeof(MultiServiceKeyedService))
+            .UsingAttributes());
+
+        Assert.Equal(2, Collection.Count);
+
+        var keyedService = Collection.First(s => s.ServiceType == typeof(IKeyedTestService));
+        Assert.Equal(typeof(MultiServiceKeyedService), keyedService.KeyedImplementationType);
+        Assert.Equal("service-key", keyedService.ServiceKey);
+
+        var otherKeyedService = Collection.First(s => s.ServiceType == typeof(IOtherKeyedTestService));
+        Assert.Equal(typeof(MultiServiceKeyedService), otherKeyedService.KeyedImplementationType);
+        Assert.Equal("other-key", otherKeyedService.ServiceKey);
+    }
+
+    [Fact]
+    public void ThrowsWhenResolvingNonExistentKeyedService()
+    {
+        var provider = ConfigureProvider(services =>
+        {
+            services.Scan(scan => scan
+                .FromTypes(typeof(KeyedTransientService))
+                .UsingAttributes());
+        });
+
+        Assert.Throws<InvalidOperationException>(() => 
+            provider.GetRequiredKeyedService<IKeyedTestService>("non-existent-key"));
+    }
+
+    [Fact]
+    public void CanRegisterKeyedServiceWithNullServiceType()
+    {
+        Collection.Scan(scan => scan
+            .FromTypes(typeof(KeyedServiceWithNullServiceType))
+            .UsingAttributes());
+
+        // Should register for the implementation type and all its interfaces
+        Assert.Equal(2, Collection.Count); // IKeyedTestService and KeyedServiceWithNullServiceType itself
+
+        var services = Collection.ToArray();
+        Assert.All(services, s => 
+        {
+            Assert.Equal("null-service-type-key", s.ServiceKey);
+            Assert.True(s.IsKeyedService);
+        });
+    }
+
+
+    [Fact]
+    public void AllowsSameServiceTypeWithDifferentKeys()
+    {
+        Collection.Scan(scan => scan
+            .FromTypes(typeof(SameServiceTypeDifferentKeys))
+            .UsingAttributes());
+
+        Assert.Equal(2, Collection.Count);
+
+        var service1 = Collection.First(s => s.ServiceKey?.ToString() == "key1");
+        var service2 = Collection.First(s => s.ServiceKey?.ToString() == "key2");
+
+        Assert.Equal(typeof(IKeyedTestService), service1.ServiceType);
+        Assert.Equal(typeof(IKeyedTestService), service2.ServiceType);
+        Assert.NotEqual(service1.ServiceKey, service2.ServiceKey);
+    }
+
+    [Fact]
+    public void CanRegisterServiceWithNullKey()
+    {
+        Collection.Scan(scan => scan
+            .FromTypes(typeof(NullKeyedService))
+            .UsingAttributes());
+
+        Assert.Single(Collection);
+
+        var service = Collection.Single();
+        Assert.Equal(typeof(IKeyedTestService), service.ServiceType);
+        Assert.Equal(typeof(NullKeyedService), service.ImplementationType);
+        Assert.Null(service.ServiceKey);
+        Assert.False(service.IsKeyedService);
+    }
+
+    [Fact]
+    public void CanResolveServiceWithNullKey()
+    {
+        var provider = ConfigureProvider(services =>
+        {
+            services.Scan(scan => scan
+                .FromTypes(typeof(NullKeyedService))
+                .UsingAttributes());
+        });
+
+        var service = provider.GetRequiredService<IKeyedTestService>();
+        Assert.IsType<NullKeyedService>(service);
+    }
+}
+
+// Test interfaces and classes for keyed services
+public interface IKeyedTestService { }
+public interface IOtherKeyedTestService { }
+
+[ServiceDescriptor(typeof(IKeyedTestService), ServiceLifetime.Transient, "test-key")]
+public class KeyedTransientService : IKeyedTestService { }
+
+[ServiceDescriptor<IKeyedTestService>(ServiceLifetime.Scoped, "generic-key")]
+public class GenericKeyedService : IKeyedTestService { }
+
+[ServiceDescriptor(typeof(IKeyedTestService), ServiceLifetime.Transient, "key1")]
+[ServiceDescriptor(typeof(IKeyedTestService), ServiceLifetime.Singleton, "key2")]
+public class MultipleKeyedService : IKeyedTestService { }
+
+[ServiceDescriptor(typeof(IKeyedTestService), ServiceLifetime.Scoped, "mixed-key")]
+[ServiceDescriptor(typeof(IKeyedTestService), ServiceLifetime.Transient)]
+public class MixedKeyedService : IKeyedTestService { }
+
+[ServiceDescriptor(typeof(IKeyedTestService), ServiceLifetime.Transient, 42)]
+public class ObjectKeyedService : IKeyedTestService { }
+
+public enum TestEnum
+{
+    Value1,
+    Value2
+}
+
+[ServiceDescriptor(typeof(IKeyedTestService), ServiceLifetime.Transient, TestEnum.Value1)]
+public class EnumKeyedService : IKeyedTestService { }
+
+[ServiceDescriptor(typeof(IKeyedTestService), ServiceLifetime.Transient, "service-key")]
+[ServiceDescriptor(typeof(IOtherKeyedTestService), ServiceLifetime.Scoped, "other-key")]
+public class MultiServiceKeyedService : IKeyedTestService, IOtherKeyedTestService { }
+
+[ServiceDescriptor(null, ServiceLifetime.Transient, "null-service-type-key")]
+public class KeyedServiceWithNullServiceType : IKeyedTestService { }
+
+
+[ServiceDescriptor(typeof(IKeyedTestService), ServiceLifetime.Transient, "key1")]
+[ServiceDescriptor(typeof(IKeyedTestService), ServiceLifetime.Scoped, "key2")]
+public class SameServiceTypeDifferentKeys : IKeyedTestService { }
+
+[ServiceDescriptor(typeof(IKeyedTestService), ServiceLifetime.Transient, null)]
+public class NullKeyedService : IKeyedTestService { }