Testably.Abstractions

Injectable abstractions for the static parts of the .NET base class library (BCL) - file system, time and randomness - with feature-complete in-memory mocks for tests.

📖 Full documentation: docs.testably.org/Abstractions

Quick example

public class ReportService(IFileSystem fileSystem)
{
    public void Save(string content)
    {
        fileSystem.Directory.CreateDirectory("reports");
        fileSystem.File.WriteAllText("reports/latest.xml", content);
    }
}

[Fact]
public async Task Save_WritesReportToReportsFolder()
{
    var fileSystem = new MockFileSystem();
    var sut = new ReportService(fileSystem);

    sut.Save("<report />");

    await Expect.That(fileSystem.File.ReadAllText("reports/latest.xml"))
        .IsEqualTo("<report />");
}

Install

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

Then register the implementations in your DI container - see Getting Started.

Packages

Package	Purpose
Testably.Abstractions	Production interfaces (IFileSystem, ITimeSystem, IRandomSystem)
Testably.Abstractions.Testing	MockFileSystem, MockTimeSystem, MockRandomSystem
Testably.Abstractions.Compression	Zip / ZipArchive extension methods on IFileSystem
Testably.Abstractions.AccessControl	GetAccessControl / SetAccessControl on files and directories
Testably.Abstractions.MemoryMappedFiles	MemoryMappedFile support on IFileSystem

Already on TestableIO?

Testably.Abstractions shares the IFileSystem interface with TestableIO.System.IO.Abstractions, so production code stays untouched. See the migration guide.

Contributing

Issues and pull requests are welcome - see CONTRIBUTING.md and the issue tracker.