Need practise in making a system testable and writing tests? See: https://github.com/ffMathy/testability-kata

FluffySpoon.Testing.Autofake

The FluffySpoon.Testing.Autofake package makes it easy for you to automatically register all your class dependencies as fakes, resulting in a setup that is easier to use with Test Driven Development (TDD) and more flexible to change in your code.

Sample using Autofac for IOC/DI and NSubstitute for faking

var containerBuilder = new ContainerBuilder();

var faker = new Autofaker();
faker.UseNSubstitute();
faker.UseAutofac(builder);

//MyClassThatIWantToTest contains two constructor parameters of types IDependency1 
//and IDependency2 respectively. these two dependencies will be registered as 
//single-instance fakes in the IOC container.
faker.RegisterFakesForConstructorParameterTypesOf<MyClassThatIWantToTest>();

var container = builder.Build();

//this instance is not faked out, because it is the class that we want to test
var myClassThatIWantToTest = container.Resolve<MyClassThatIWantToTest>();

//these instances are fakes and single-instance, because they are constructor 
//parameters of MyClassThatIWantToTest.
var fakeDependency1 = container.Resolve<IDependency1>();
var fakeDependency2 = container.Resolve<IDependency2>();

Dependency Injection and Inversion of Control systems

Autofac

Package: FluffySpoon.Testing.Autofake.Autofac

var builder = new ContainerBuilder();

var faker = new Autofaker();
faker.UseAutofac(builder);

faker.RegisterFakesForConstructorParameterTypesOf<MyClassThatIWantToTest>();

var container = builder.Build();

Microsoft's Dependency Injection (used in ASP .NET Core and .NET Core)

Package: FluffySpoon.Testing.Autofake.MicrosoftDependencyInjection

var serviceCollection = new ServiceCollection();

var faker = new Autofaker();
faker.UseMicrosoftDependencyInjection(serviceCollection);

faker.RegisterFakesForConstructorParameterTypesOf<MyClassThatIWantToTest>();

var serviceProvider = serviceCollection.BuildServiceProvider();

StructureMap

Package: FluffySpoon.Testing.Autofake.StructureMap

var container = new Container();

var faker = new Autofaker();
faker.UseStructureMap(container);

faker.RegisterFakesForConstructorParameterTypesOf<MyClassThatIWantToTest>();

Lamar

Package: FluffySpoon.Testing.Autofake.Lamar

var container = new Container(serviceRegistry => {
	var faker = new Autofaker();
	faker.UseLamar(serviceRegistry);

	faker.RegisterFakesForConstructorParameterTypesOf<MyClassThatIWantToTest>();
});

Faking frameworks

NSubstitute

Package: FluffySpoon.Testing.Autofake.NSubstitute

var faker = new Autofaker();
faker.UseNSubstitute();

...

var fakeClassDependency = container.Resolve<IFakeClassDependency>();
fakeClassDependency.SayFoo().Returns("fakefoo");

fakeClassDependency.SayFoo(); //returns "fakefoo"

FakeItEasy

Package: FluffySpoon.Testing.Autofake.FakeItEasy

var faker = new Autofaker();
faker.UseFakeItEasy();

...

var fakeClassDependency = container.Resolve<IFakeClassDependency>();
A.CallTo(() => fakeClassDependency.SayFoo()).Returns("fakefoo");

fakeClassDependency.SayFoo(); //returns "fakefoo"

Moq

Package: FluffySpoon.Testing.Autofake.Moq

var faker = new Autofaker();
faker.UseMoq();

...

var fakeClassDependencyMock = container.Resolve<IMock<IFakeClassDependency>>();
fakeClassDependencyMock.Setup(x => x.SayFoo()).Returns("fakefoo");

var fakeClassDependency = container.Resolve<IFakeClassDependency>();
fakeClassDependency.SayFoo(); //returns "fakefoo"