SUT Forge

Introduction

Experience unit testing and Test-Driven Development (TDD) in a whole new light with SUTForge, a simple yet powerful .NET package meticulously designed to streamline the creation of System Under Test (SUT) instances. SUTForge follows the Chicago School to unit testing (also referred to as the Classical School of unit testing), offering a clean and efficient alternative to the over-mocking issues associated with the London approach. What sets SUTForge apart is its high degree of extensibility, allowing developers to craft personalized extension methods and tailor SUTs to their specific testing needs.

Key Features:

• Effortless TDD Integration: SUTForge seamlessly integrates with Test-Driven Development (TDD), enabling developers to write tests first and then effortlessly construct and configure their SUTs using the intuitive builder pattern provided by SUTForge.

• Classical Approach to Unit Testing: Embrace the classical approach to unit testing, emphasizing simplicity and readability. SUTForge encourages clean and maintainable tests without succumbing to over-mocking pitfalls, ensuring your unit tests remain valuable assets throughout the development lifecycle.

• Intuitive Builder Pattern: Constructing SUTs becomes a breeze with SUTForge's intuitive builder pattern. Say goodbye to the complexities of manual setup and embrace a syntax that makes unit test code concise, expressive, and easy to understand.

• Highly Extensible: SUTForge goes beyond the basics, offering developers a high degree of extensibility. Write your own extension methods to customize SUTs according to your unique testing requirements. Tailor SUTForge to fit seamlessly into your specific development workflow.

💪 Elevate your unit testing and TDD experience with SUTForge—a library that not only embraces the classical approach but also empowers you to extend and customize your testing capabilities. Your journey to efficient and maintainable tests starts here!

Getting Started

To get started with SUTForge, you need to install the package in your .NET project. Once installed, you can start writing your unit tests using the SUTForge's intuitive builder pattern.

Installation

Install SUTForge via NuGet package manager:

Install-Package SUTForge

Writing Your First Test

Here's an example of how you can write a unit test using SUTForge. This test checks whether a service is correctly built by the builder.

[Test]
public async Task Services_are_built_by_the_builder()
{
    // Arrange
    // Act
    var sut = await SutBuilder.Create
        .ConfigureServices(services => { services.AddSingleton<ISomeInterface, SomeImplementation>(); })
        .BuildAsync();

    // Assert
    sut.Should().NotBeNull();
    sut.GetService<ISomeInterface>().Should().NotBeNull().And.BeOfType<SomeImplementation>();
}

In the above test, we're using the SutBuilder.Create method to create a new instance of the SUT builder. We then configure the services by adding a singleton service of type ISomeInterface with an implementation of SomeImplementation. After building the SUT, we assert that the SUT is not null and that the service of type ISomeInterface is not null and is of type SomeImplementation.

Resolving Configuration for Services

SUTForge also allows you to resolve configurations for services. Here's an example:

[Test]
public async Task Configuration_is_resolved_for_services()
{
    // Arrange
    // Act
    var sut = await SutBuilder.Create
        .ConfigureServices(services => { services.AddSingleton<ClassWithConfiguration>(); })
        .BuildAsync();

    // Assert
    sut.GetService<ClassWithConfiguration>().Should().NotBeNull();
}

In this test, we're adding a service of type ClassWithConfiguration that requires configuration. After building the SUT, we assert that the service of type ClassWithConfiguration is not null, implying that the configuration was resolved correctly.

Customizing Configuration

SUTForge also allows you to customize the configuration. Here's an example:

[Test]
public async Task Configuration_can_be_customized()
{
    // Arrange
    // Act
    var sut = await SutBuilder.Create
        .ConfigureServices(services => { services.AddSingleton<ClassWithConfiguration>(); })
        .OnSetupConfiguration(builder => builder.AddInMemoryCollection(new Dictionary<string, string>
        {
            {"Country", "France"}
        }))
        .BuildAsync();

    // Assert
    var service = sut.GetService<ClassWithConfiguration>();
    service.Should().NotBeNull();
    service.Configuration["Country"].Should().Be("France");
}

In this test, we're customizing the configuration by adding an in-memory collection with a key-value pair of "Country" and "France". After building the SUT, we assert that the service of type ClassWithConfiguration is not null and that the configuration value for "Country" is "France".

Extending SUTForge

SUTForge is highly extensible, allowing you to write your own extension methods to customize SUTs according to your unique testing requirements. Here's an example:

public static class SutBuilderExtensions
{
    public static SutBuilder WithCurrentTime(this SutBuilder builder, DateTime time)
    {
        return builder.ConfigureServices(services => { services.AddSingleton<ITimeProvider(new DeterministicTimeProvider(time)); });
    }
}   

In this example, we're writing an extension method that allows us to customize the SUT by adding a singleton service of type ITimeProvider with an implementation of DeterministicTimeProvider. This extension method can then be used in our tests as follows:

[Test]
public async Task SUT_can_be_customized()
{
    // Arrange
    var time = 14.January(2021).At(12, 0, 0).AsUtc(); // Using FluentAssertions
    
    var sut = await SutBuilder.Create
        .AddApplicationServices() // Add the application services
        .WithCurrentTime(time)
        .BuildAsync();
    
    var service = sut.GetRequiredService<ISomeFancyService>();
    
    // Act
    var result = service.DoSomething();

    // Assert
    // Assert something
}

With SUTForge, writing unit tests becomes a breeze. Embrace the classical approach to unit testing and elevate your TDD experience with SUTForge. Happy testing!

References

• Unit Testing Principles, Practices, and Patterns (Vladimir Khorikov)
• 🚀 TDD, Where Did It All Go Wrong (Ian Cooper)
• Uncle Bob (Robert C. Martin), TDD Harms Architecture https://blog.cleancoder.com/uncle-bob/2017/03/03/TDD-Harms-Architecture.html (On a shift from London to Chicago School of TDD; About fallacy of Test file pattern)
• TDD Revisited - Ian Cooper - NDC London 2021 (on testing “ports&adapters” architecture with Chicago School of TDD)