SlowFox.Core 0.2.0

Introduction

SlowFox is a suite of .NET source generators, aiming to reduce the amount of repetitive code you need to write and maintain.

Source generators incur no run-time cost (as no reflection is involved), because the code is created at build time. Plus, using a supported IDE (like Visual Studio 2019/2022), you can see what's being generated immediately when you save your source code.

There are currently 2 generators available via SlowFox:

1. Constructors, for generating constructors and private variables
2. UnitTestMocks, for generating mock objects in unit tests

SlowFox.Constructors

SloxFox.Constructors is a generator that allows you to define the injectable dependencies for any given class, and the private class members, constructor and constructor assignments are all automatically created for you.

How do I get it working?

First off, install the NuGet package into your project:

Then, find a class where you want to have the dependencies injected, mark it as partial, and add the SlowFox.InjectDependencies attribute. Pass into this attribute the types you want to be injected:

namespace MySampleProject
{
    [SlowFox.InjectDependencies(typeof(IUserReader), typeof(IFileHandler))]
    public partial class MyNewClass
    {
    }
}

SlowFox will then generate everything needed for these dependencies, as another partial class:

namespace MySampleProject
{
    public partial class MyNewClass
    {
        private readonly IUserReader _userReader;
        private readonly IFileHandler _fileHandler;

        public MyNewClass(IUserReader userReader, IFileHandler fileHandler)
        {
            _userReader = userReader;
            _fileHandler = fileHandler;
        }
    }
}

You can reference these private members in your original class, and you can call this constructor during DI, or call it manually, or use it in unit tests - it's as if you've written it all yourself:

namespace MySampleProject
{
    [SlowFox.InjectDependencies(typeof(IUserReader), typeof(IFileHandler))]
    public partial class MyNewClass
    {
        public void SaveUserImage()
        {
            var image = _userReader.GetImage();
            _fileHandler.AddFile(image);
        }
    }
}

This generator is compatible with:

• inheritance
• abstract classes
• generic types
• nullable types
• tuples

Configuration

Configuration is set in a .editorconfig file.

To configure the generated code to not use underscores for member names, set the skip_underscores value to true:

[*.cs]
slowfox_generation.constructors.skip_underscores = true

To include a null check (and a throw of ArgumentNullException if the constructor parameter is null), set include_nullcheck to true:

[*.cs]
slowfox_generation.constructors.include_nullcheck = true

SlowFox.UnitTestMocks

SlowFox.UnitTestMocks is a generator that creates mock objects (using Moq) for the dependencies of a class that is to be tested.

There are packages that are designed for xUnit, NUnit and MSTest2.

How do I get it working?

Firstly, choose and install the NuGet package relating to your testing framework:

Framework	Package
xUnit
NUnit
MSTest2

Next, create a new test class, mark it as partial and apply the InjectMocks attribute, indicating the class that you're going to be tested:

namespace MySampleProject
{
    [SlowFox.InjectMocks(typeof(UserHandler))]
    public partial class UserHandlerTests
    {
    }
}

SlowFox will then generate mock objects for each dependency of the selected class, and provide a Create method that instantiates a new instance of the selected class with the mock objects used as dependencies:

namespace MySampleProject
{
    public partial class UserHandlerTests
    {
        private Mock<IDatabase> _database;
        private Mock<ILogger> _logger;

        public UserHandlerTests()
        {
            _database = new Mock<IDatabase>(MockBehavior.Strict);
            _logger = new Mock<ILogger>(MockBehavior.Strict);
        }

        private UserHandler Create()
        {
            return new UserHandler(_database.Object, _logger.Object);
        }
    }
}

For NUnit and MSTest, the mocks are instantiated in a Setup and Init method respectively, instead of in a constructor

You can call Create() in your tests to get the object to test, and you can reference the mock objects to set up any pre-defined responses, or to perform validation:

namespace MySampleProject
{
    [SlowFox.InjectMocks(typeof(UserHandler))]
    public partial class UserHandlerTests
    {
        [Fact]
        public void VerifyAddUser()
        {
            _database
                .Setup(p => p.Save(It.IsAny<User>()));

            UserHandler reader = Create();

            reader.CreateNewUser();

            _database
                .Verify(p => p.Save(It.IsAny<User>()), Times.Once);
        }
    }
}

You are able to exclude specific types from being mocked, by using the ExcludeMocks attribute. Any type specified within this attribute will be added as a parameter on the Create method, so you can provide a value from within your test:

namespace MySampleProject
{
    [SlowFox.InjectMocks(typeof(UserHandler))]
    [SlowFox.ExcludeMocks(typeof(ILogger))]
    public partial class UserHandlerTests
    {
        [Fact]
        public void VerifyAddUser()
        {
            _database
                .Setup(p => p.Save(It.IsAny<User>()));

            ILogger testLogger = BuildTestLogger();

            UserHandler reader = Create(testLogger);

            reader.CreateNewUser();

            _database
                .Verify(p => p.Save(It.IsAny<User>()), Times.Once);
        }
    }
}

Note that types that cannot be mocked (e.g., a static or sealed type) will automatically be excluded from being mocked, and will be treated in the same way as types specified in the ExcludeMocks attribute

This generator is compatible with constructors that have been generated using SlowFox.Constructors.

Configuration

Configuration is set in a .editorconfig file.

To configure the generated code to not use underscores for member names, set the skip_underscores value to true:

[*.cs]
slowfox_generation.unit_test_mocks.xunit.skip_underscores = true

To create the mocks using the Loose behaviour (instead of the default of Strict), set the use_loose value to be true:

[*.cs]
slowfox_generation.unit_test_mocks.xunit.use_loose = true

These configuration keys are different for NUnit and MSTest. For NUnit the configuration prefix is slowfox_generation.unit_test_mocks.nunit and for MSTest the prefix is slowfox_generation.unit_test_mocks.mstest

Can I help fix any bugs with this, or add new capabilities?

Of course! Head on over to the issues page, raise it, and we'll have a chat about what needs to be done.