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Getting Started

1. Install the packages​

Install Testably.Abstractions in your production projects and Testably.Abstractions.Testing in your test projects:

dotnet add package Testably.Abstractions
dotnet add package Testably.Abstractions.Testing

Optional companion packages:

dotnet add package Testably.Abstractions.Compression
dotnet add package Testably.Abstractions.AccessControl

2. Register the abstractions​

With Microsoft.Extensions.DependencyInjection:

builder.Services
    .AddSingleton<IFileSystem, RealFileSystem>()
    .AddSingleton<IRandomSystem, RealRandomSystem>()
    .AddSingleton<ITimeSystem, RealTimeSystem>();

3. Use the interfaces in your services​

public class MyService(IFileSystem fileSystem)
{
    private readonly IFileSystem _fileSystem = fileSystem;

    public void StoreData()
    {
        _fileSystem.File.WriteAllText("result.xml", GetFileContent());
    }

    private string GetFileContent() => /* ... */;
}

4. Replace the real implementations in tests​

[Test]
public void StoreData_ShouldWriteValidFile()
{
    IFileSystem fileSystem = new MockFileSystem();
    var sut = new MyService(fileSystem);

    sut.StoreData();

    var content = fileSystem.File.ReadAllText("result.xml");
    // assert on content
}

That's it - your code now runs against an in-memory file system in tests, and against the real one in production.

Next steps​

  • File system - IFileSystem, MockFileSystem, drives, watcher, statistics, strategies.
  • Time system - ITimeSystem, time providers, timers, auto-advance, notifications.
  • Random system - IRandomSystem and deterministic generators.
  • Companion libraries - Compression and AccessControl.