Add default bindings for Named Factory

README.md

@@ -208,7 +208,10 @@ public void ConfigureServices(IServiceCollection services)
 Implementation for `IRepositoryFactory` will be generated at runtime.
 
 In fact, each factory method can take one parameter of an arbitrary type - string, enum, custom class, whatever.
-In this case, a _named binding_ should be specified.
+In this case, a _named binding_ should be specified. Then you may resolve required services passing the name of
+the binding into factory methods. If you want to provide a default implementation then you may configure _default
+binding_. Default binding is such a binding used in the absence of a named one. A user should set default binding
+explicitly to be able to resolve services for unregistered names.
 
 ```csharp
 public interface IRepositoryFactory
@@ -236,6 +239,11 @@ public class RandomRepository : IRepository
 ...
 }
 
+public class DefaultRepository : IRepository
+{
+...
+}
+
 public void ConfigureServices(IServiceCollection services)
 {
     services.AddTransient<IRepository, DemoRepository>()
@@ -245,7 +253,8 @@ public void ConfigureServices(IServiceCollection services)
                 .For<IRepository>()
                     .Named<DemoRepository>("demo")
                     .Named<ProductionRepository>("prod")
-                    .Named<RandomRepository>("rnd");
+                    .Named<RandomRepository>("rnd")
+                    .Default<DefaultRepository>();
 }
 
 public class Person
@@ -262,20 +271,24 @@ public class SomeClassWithDependency
         _factory = factory;
     }
 
+    private bool SomeInterestingCondition => ...
+
     public void DoSomething(Person person)
     {
         if (person.Name == "demoUser")
-            _factory.GetPersonsRepo("demo").Save(person);
+            _factory.GetPersonsRepo("demo").Save(person); // DemoRepository
         else if (person.Name.StartsWith("tester"))
-            _factory.GetPersonsRepo("rnd").Save(person);
+            _factory.GetPersonsRepo("rnd").Save(person); // RandomRepository
+        else if (SomeInterestingCondition)
+            _factory.GetPersonsRepo("prod").Save(person); // ProductionRepository
         else
-            _factory.GetPersonsRepo("prod").Save(person);
+            _factory.GetPersonsRepo(person.Name).Save(person); // DefaultRepository
     }
 }
 ```
 
 In the example above, the `GetPersonsRepo` method will return the corresponding implementation of the `IRepository`
-interface, configured for the provided name.
+interface, configured for the provided name. For all unregistered names (including null) it will return `DefaultRepository`.
 
 ## How it works?
 

src/SteroidsDI.Tests/Cases.Approval/ApiApprovalTests.cs

@@ -17,13 +17,13 @@ public class ApiApprovalTests
     [TestCase(typeof(AspNetCoreHttpScopeProvider))]
     public void PublicApi(Type type)
     {
-        string publicApi = type.Assembly.GeneratePublicApi(new ApiGeneratorOptions
+        string publicApi = type.Assembly.GeneratePublicApi(new()
         {
             IncludeAssemblyAttributes = false,
             AllowNamespacePrefixes = ["System", "Microsoft.Extensions.DependencyInjection"],
             ExcludeAttributes = ["System.Diagnostics.DebuggerDisplayAttribute"],
         });
 
-        publicApi.ShouldMatchApproved(options => options!.WithFilenameGenerator((testMethodInfo, discriminator, fileType, fileExtension) => $"{type.Assembly.GetName().Name!}.{fileType}.{fileExtension}"));
+        publicApi.ShouldMatchApproved(options => options.NoDiff().WithFilenameGenerator((testMethodInfo, discriminator, fileType, fileExtension) => $"{type.Assembly.GetName().Name!}.{fileType}.{fileExtension}"));
     }
 }

src/SteroidsDI.Tests/Cases.Approval/SteroidsDI.approved.txt

@@ -19,9 +19,13 @@ namespace SteroidsDI
     {
         public BindingContext(Microsoft.Extensions.DependencyInjection.IServiceCollection services) { }
         public Microsoft.Extensions.DependencyInjection.IServiceCollection Services { get; }
+        public SteroidsDI.BindingContext<TService> Default<TImplementation>()
+            where TImplementation : TService { }
+        public SteroidsDI.BindingContext<TService> Default<TImplementation>(Microsoft.Extensions.DependencyInjection.ServiceLifetime lifetime)
+            where TImplementation : TService { }
         public SteroidsDI.BindingContext<TService> Named<TImplementation>(object name)
             where TImplementation : TService { }
-        public SteroidsDI.BindingContext<TService> Named<TImplementation>(object name, Microsoft.Extensions.DependencyInjection.ServiceLifetime lifetime = 2)
+        public SteroidsDI.BindingContext<TService> Named<TImplementation>(object name, Microsoft.Extensions.DependencyInjection.ServiceLifetime lifetime)
             where TImplementation : TService { }
     }
     public sealed class GenericScopeProvider<T> : SteroidsDI.Core.IScopeProvider

src/SteroidsDI.Tests/Cases/FactoryTests.cs

@@ -15,14 +15,61 @@ public void Named_Binding_Should_Throw_On_Unknown_Lifetime()
     {
         var services = new ServiceCollection();
         var context = services.For<IBuilder>();
-        Should.Throw<InvalidOperationException>(() => context.Named<SpecialBuilder>("xxx")).Message.ShouldBe(@"The DI container does not have a default binding for the type 'SteroidsDI.Tests.IBuilder', so it is not possible to determine the value of Lifetime.
-Use the 'Named' overload with explicit Lifetime or first set the default binding in the DI container.");
+        Should.Throw<InvalidOperationException>(() => context.Named<SpecialBuilder>("xxx")).Message.ShouldBe(@"The DI container does not register type 'SteroidsDI.Tests.IBuilder', so it is not possible to determine the value of Lifetime.
+Use the 'Named'/'Default' overloads with explicit Lifetime or first register 'SteroidsDI.Tests.IBuilder' in the DI container.");
+        Should.Throw<InvalidOperationException>(() => context.Default<SpecialBuilder>()).Message.ShouldBe(@"The DI container does not register type 'SteroidsDI.Tests.IBuilder', so it is not possible to determine the value of Lifetime.
+Use the 'Named'/'Default' overloads with explicit Lifetime or first register 'SteroidsDI.Tests.IBuilder' in the DI container.");
     }
 
     [Test]
-    public void Factory_And_Named_Bindings_Should_Work()
+    public void Named_Binding_Should_Allow_The_Same_Type_With_Different_Names()
     {
-        using var provider = ServicesBuilder.BuildDefault().BuildServiceProvider(validateScopes: true);
+        var services = new ServiceCollection()
+            .AddTransient<IBuilder, Builder>()
+            .For<IBuilder>()
+                .Named<SpecialBuilder>("aaa")
+                .Named<SpecialBuilder>("bbb")
+                .Named<SpecialBuilder>("ccc")
+            .Services;
+        services.Count.ShouldBe(5);
+    }
+
+    [Test]
+    public void Default_Binding_Should_Allow_Redeclaration()
+    {
+        var services = new ServiceCollection()
+            .AddTransient<IBuilder, Builder>()
+            .For<IBuilder>()
+                .Default<SpecialBuilder>()
+                .Default<SpecialBuilder>()
+            .Services;
+        services.Count.ShouldBe(3);
+        var def = (NamedBinding)services.Last().ImplementationInstance!;
+        def.Name.ShouldBeNull();
+        def.ImplementationType.ShouldBe(typeof(SpecialBuilder));
+    }
+
+    [Test]
+    public void Default_Binding_Should_Allow_Replace()
+    {
+        var services = new ServiceCollection()
+            .AddTransient<IBuilder, Builder>()
+            .For<IBuilder>()
+                .Default<SpecialBuilder>()
+                .Default<SpecialBuilderOver9000Level>()
+            .Services;
+        services.Count.ShouldBe(4);
+        var def = (NamedBinding)services[2].ImplementationInstance!;
+        def.Name.ShouldBeNull();
+        def.ImplementationType.ShouldBe(typeof(SpecialBuilderOver9000Level));
+    }
+
+    [Test]
+    [TestCase(true)]
+    [TestCase(false)]
+    public void Factory_And_Named_Bindings_Should_Work(bool useDefault)
+    {
+        using var provider = ServicesBuilder.BuildDefault(addDefalt: useDefault).BuildServiceProvider(validateScopes: true);
         using var scope = provider.CreateScope();
 
         GenericScope<ServicesBuilder>.CurrentScope = scope;
@@ -59,10 +106,12 @@ public void Factory_And_Named_Bindings_Should_Work()
     }
 
     [Test]
+    [TestCase(true)]
+    [TestCase(false)]
     [Category("Generic")]
-    public void Generic_Factory_And_Named_Bindings_Should_Work()
+    public void Generic_Factory_And_Named_Bindings_Should_Work(bool useDefault)
     {
-        using var provider = ServicesBuilder.BuildDefault().BuildServiceProvider(validateScopes: true);
+        using var provider = ServicesBuilder.BuildDefault(addDefalt: useDefault).BuildServiceProvider(validateScopes: true);
         using var scope = provider.CreateScope();
 
         GenericScope<ServicesBuilder>.CurrentScope = scope;
@@ -100,35 +149,91 @@ public void Generic_Factory_And_Named_Bindings_Should_Work()
 
     [Test]
     [Category("Throw")]
-    public void Null_Binding_Should_Throw()
+    public void Null_Binding_Should_Throw_When_No_Default()
     {
         using var provider = ServicesBuilder.BuildDefault().BuildServiceProvider(validateScopes: true);
         var controller = provider.GetRequiredService<Controller>();
 
-        Should.Throw<InvalidOperationException>(() => controller.Factory.CCC(null!));
-        Should.Throw<InvalidOperationException>(() => controller.Generic.CCC(null!));
+        var msg1 = Should.Throw<InvalidOperationException>(() => controller.Factory.CCC(null!)).Message;
+        msg1.ShouldBe("Destination type not found for named binding '' to type 'SteroidsDI.Tests.IBuilder' and no default binding exists. Verify that either a named binding or default binding is specified in the DI container.");
+        var msg2 = Should.Throw<InvalidOperationException>(() => controller.Generic.CCC(null!)).Message;
+        msg2.ShouldBe("Destination type not found for named binding '' to type 'SteroidsDI.Tests.IBuilder' and no default binding exists. Verify that either a named binding or default binding is specified in the DI container.");
     }
 
     [Test]
-    [Category("Throw")]
-    public void Unknown_Binding_Should_Throw()
+    public void Null_Binding_Should_Work_When_Default()
+    {
+        using var provider = ServicesBuilder.BuildDefault(addDefalt: true).BuildServiceProvider(validateScopes: true);
+        var controller = provider.GetRequiredService<Controller>();
+
+        var builder1 = controller.Factory.CCC(null!);
+        builder1.ShouldBeAssignableTo<DefaultBuilder>();
+        builder1.Build();
+
+        var builder2 = controller.Generic.CCC(null!);
+        builder2.ShouldBeAssignableTo<DefaultBuilder>();
+        builder2.Build();
+    }
+
+    [Test]
+    public void Unknown_Binding_Should_Throw_When_No_Default()
     {
         using var provider = ServicesBuilder.BuildDefault().BuildServiceProvider(validateScopes: true);
         var controller = provider.GetRequiredService<Controller>();
 
-        Should.Throw<InvalidOperationException>(() => controller.Factory.CCC("Zorro"));
-        Should.Throw<InvalidOperationException>(() => controller.Generic.CCC("Zorro"));
+        var msg1 = Should.Throw<InvalidOperationException>(() => controller.Factory.CCC("Zorro")).Message;
+        msg1.ShouldBe("Destination type not found for named binding 'Zorro' to type 'SteroidsDI.Tests.IBuilder' and no default binding exists. Verify that either a named binding or default binding is specified in the DI container.");
+        var msg2 = Should.Throw<InvalidOperationException>(() => controller.Generic.CCC("Zorro")).Message;
+        msg2.ShouldBe("Destination type not found for named binding 'Zorro' to type 'SteroidsDI.Tests.IBuilder' and no default binding exists. Verify that either a named binding or default binding is specified in the DI container.");
 
-        Should.Throw<InvalidOperationException>(() => controller.Factory.DDD(ManagerType.Angry));
-        Should.Throw<InvalidOperationException>(() => controller.Generic.DDD(ManagerType.Angry));
+        var msg3 = Should.Throw<InvalidOperationException>(() => controller.Factory.DDD(ManagerType.Angry)).Message;
+        msg3.ShouldBe("Destination type not found for named binding 'Angry' to type 'SteroidsDI.Tests.IBuilder' and no default binding exists. Verify that either a named binding or default binding is specified in the DI container.");
+        var msg4 = Should.Throw<InvalidOperationException>(() => controller.Generic.DDD(ManagerType.Angry)).Message;
+        msg4.ShouldBe("Destination type not found for named binding 'Angry' to type 'SteroidsDI.Tests.IBuilder' and no default binding exists. Verify that either a named binding or default binding is specified in the DI container.");
+    }
+
+    [Test]
+    [Category("Throw")]
+    public void Unknown_Binding_Should_Work_When_Default()
+    {
+        using var provider = ServicesBuilder.BuildDefault(addDefalt: true).BuildServiceProvider(validateScopes: true);
+        var controller = provider.GetRequiredService<Controller>();
+
+        var builder1 = controller.Factory.CCC("Zorro");
+        builder1.ShouldBeAssignableTo<DefaultBuilder>();
+        builder1.Build();
+
+        var builder2 = controller.Generic.CCC("Zorro");
+        builder2.ShouldBeAssignableTo<DefaultBuilder>();
+        builder2.Build();
+
+        var builder3 = controller.Factory.DDD(ManagerType.Angry);
+        builder3.ShouldBeAssignableTo<DefaultBuilder>();
+        builder3.Build();
+
+        var builder4 = controller.Generic.DDD(ManagerType.Angry);
+        builder4.ShouldBeAssignableTo<DefaultBuilder>();
+        builder4.Build();
     }
 
     [Test]
     [Category("Throw")]
     public void Named_Binding_With_Invalid_Properties_Should_Throw()
     {
-        Should.Throw<ArgumentNullException>(() => ServicesBuilder.BuildDefault().For<IBuilder>().Named<SpecialBuilder>(null!).Services.BuildServiceProvider(validateScopes: true));
-        Should.Throw<InvalidOperationException>(() => ServicesBuilder.BuildDefault().For<IBuilder>().Named<SpecialBuilderOver9000Level>("oops", ServiceLifetime.Transient).Services.BuildServiceProvider(validateScopes: true));
+        var msg1 = Should.Throw<ArgumentNullException>(() => ServicesBuilder.BuildDefault().For<IBuilder>().Named<SpecialBuilder>(null!).Services.BuildServiceProvider(validateScopes: true)).Message;
+        msg1.ShouldBe("No binding name specified. (Parameter 'name')");
+        var msg2 = Should.Throw<InvalidOperationException>(() => ServicesBuilder.BuildDefault().For<IBuilder>().Named<SpecialBuilderOver9000Level>("oops", ServiceLifetime.Transient).Services.BuildServiceProvider(validateScopes: true)).Message;
+        msg2.ShouldBe(@"It is not possible to add a named binding 'oops' for type SteroidsDI.Tests.IBuilder, because the DI container
+already has a binding on type SteroidsDI.Tests.SpecialBuilderOver9000Level with different characteristics. This is a limitation of the current implementation.");
+    }
+
+    [Test]
+    [Category("Throw")]
+    public void Default_Binding_With_Invalid_Properties_Should_Throw()
+    {
+        var msg = Should.Throw<InvalidOperationException>(() => ServicesBuilder.BuildDefault(addDefalt: true).For<IBuilder>().Default<DefaultBuilder>(ServiceLifetime.Transient).Services.BuildServiceProvider(validateScopes: true)).Message;
+        msg.ShouldBe(@"It is not possible to add a default binding for type SteroidsDI.Tests.IBuilder, because the DI container
+already has a binding on type SteroidsDI.Tests.DefaultBuilder with different characteristics. This is a limitation of the current implementation.");
     }
 
     [Test]

src/SteroidsDI.Tests/Model/IBuilder.cs

@@ -19,3 +19,8 @@ internal class SpecialBuilderOver9000Level : IBuilder
 {
     public void Build() => Console.WriteLine("!!!!!!!SpecialBuilderOver9000Level!!!!!!!");
 }
+
+internal class DefaultBuilder : IBuilder
+{
+    public void Build() => Console.WriteLine("Default");
+}

src/SteroidsDI.Tests/ServicesBuilder.cs

@@ -5,7 +5,7 @@ namespace SteroidsDI.Tests;
 
 internal class ServicesBuilder
 {
-    public static IServiceCollection BuildDefault(bool addScopeProvider = true)
+    public static IServiceCollection BuildDefault(bool addScopeProvider = true, bool addDefalt = false)
     {
         var services = new ServiceCollection()
             .AddDefer()
@@ -19,14 +19,17 @@ public static IServiceCollection BuildDefault(bool addScopeProvider = true)
             .AddFactory<IMegaFactory>()
             .AddFactory<IGenericFactory<IBuilder, INotifier>>()
             .AddTransient<IBuilder, Builder>()
-            .AddSingleton<INotifier, Notifier>()
-            .For<IBuilder>()
-                .Named<SpecialBuilder>("xxx")
-                .Named<SpecialBuilder>("yyy")
-                .Named<SpecialBuilderOver9000Level>("oops", ServiceLifetime.Singleton)
-                .Named<SpecialBuilder>(ManagerType.Good)
-                .Named<SpecialBuilderOver9000Level>(ManagerType.Bad, ServiceLifetime.Singleton)
-      .Services;
+            .AddSingleton<INotifier, Notifier>();
+
+        var context = services.For<IBuilder>()
+            .Named<SpecialBuilder>("xxx")
+            .Named<SpecialBuilder>("yyy")
+            .Named<SpecialBuilderOver9000Level>("oops", ServiceLifetime.Singleton)
+            .Named<SpecialBuilder>(ManagerType.Good)
+            .Named<SpecialBuilderOver9000Level>(ManagerType.Bad, ServiceLifetime.Singleton);
+
+        if (addDefalt)
+            context.Default<DefaultBuilder>(ServiceLifetime.Singleton);
 
         if (addScopeProvider)
             services.AddSingleton<IScopeProvider, GenericScopeProvider<ServicesBuilder>>();