Suggestion: Platform-Specific Derivations of SkipAttribute (e.g., RunOnlyOnWindowsAttribute)

[samtrion]

I'd like to propose adding platform-specific derivations of the existing [Skip] to better support conditional test execution across runtime environments.

Suggested attributes:

• RunOnlyOnWindowsAttribute
• RunNotOnWindowsAttribute
• RunOnlyOnLinuxAttribute
• RunNotOnLinuxAttribute
• RunOnlyOnMacOsAttribute
• RunNotOnMacOsAttribute

Motivation

In real-world .NET projects—especially those targeting multiple platforms or maintaining legacy support for .NET Framework—it's common to encounter tests that are only valid under certain operating systems. Currently, developers often use inline checks or rely on third-party solutions to manage this. While that works, it's not ideal.

These new attributes would provide:

• Clear semantic intent — The test itself declares under which OS it should (not) run.
• Cleaner test code — Avoids cluttering the test body with platform checks, or compiler switches.
• Better maintainability — Easier to see and understand environmental constraints.
• CI/CD reliability — Prevents false negatives in heterogeneous test pipelines.
• No third-party dependencies — Unlike xUnit, where solutions like SkippableFact or ConditionalFact often require additional packages or custom implementations.

Why now?

Introducing these attributes early would strengthen TUnit's positioning as a pragmatic, developer-centric testing framework. It would add clarity, eliminate friction, and improve test hygiene—especially in modern development environments that combine legacy systems with cross-platform .NET code.

Happy to contribute a PR if there's interest. Looking forward to your thoughts!

[thomhurst]

Happy to bake these in. I've actually needed them myself in my test project: https://github.com/thomhurst/TUnit/blob/feature/refactor-contexts/TUnit.TestProject/WindowsOnlyAttribute.cs

We can probably just reduce it to two attributes with an operating system enum

[RunOn(...)]

[ExcludeOn(...)]

This would allow easily specifying multiple values if the enum uses flags too.

[RunOn(OS.Linux | OS.MacOS)]

[samtrion]

That sounds even more promising, and I really like the direction with [RunOn(...)] and [ExcludeOn(...)] using an OS enum—especially with support for flags to target multiple platforms at once.

That said, one potential concern might be additional boilerplate, particularly when it comes to ensuring compatibility with .NET Framework. Depending on how the platform detection is implemented (e.g., relying on RuntimeInformation or similar APIs), we may need to consider fallback mechanisms or conditional compilation to maintain support for older targets.

Still, the consolidation into just two attributes is elegant and future-ready.

[thomhurst]

Yeah. Compilational if statements is what I've done personally.

Pseudo-code:

ShouldSkip()
{
#if NET STANDARD
return OsEnum != Windows;
#else

if(OsEnum.HasFlag(Windows)  && OperatingSystem.IsWindows()) return false;

if(OsEnum.HasFlag(Mac)  && OperatingSystem.IsMac()) return false;

if(OsEnum.HasFlag(Linux)  && OperatingSystem.IsLinux()) return false;

return true;
#endif
}

[samtrion]

I will be happy to create a PR for this.

[thomhurst]

Go for it 😄