With .NET 10, C# now supports single file apps. And with a bit of work, this means we can also create single file test suites, which can be useful in a variety of scenarios!

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.NET 10 introduces file-based C# programs that can be run with `dotnet run <file.cs>`. This article demonstrates how to create single-file test suites using xUnit v3 by adding package references with `#:package` syntax, implementing a test runner with callbacks for test results, and writing test classes in the same file. The boilerplate can be simplified using the Ardalis.SingleFileTestRunner.xUnitV3 NuGet package. Tests can reference other projects using `#:project` directives and integrate into CI/CD pipelines. Benefits include zero project scaffolding, fast iteration, portability, and ease of sharing executable examples.

Single File Test Suites in Dotnet Csharp

Building xUnit Tests as File-Based C# Programs