Writing A Windows-only method-level attribute for xUnit in C# & .NET

Yesterday’s post, “Writing Operating Specific Test Assertion For xUnit In C# & .NET”, discussed how to write an assertion that runs only under a specific condition: the operating system is Windows.

If you have many of these tests, it can become repetitive and annoying to keep specifying the condition for each assertion in code.

A solution to this is to create an attribute at the method level, such that the entire test is run (or skipped) depending on the attribute.

It will look like this:

[AttributeUsage(AttributeTargets.Method)]
public sealed class WindowsOnlyFactAttribute : FactAttribute
{
    public WindowsOnlyFactAttribute()
    {
        if (!OperatingSystem.IsWindows())
        {
            Skip = "This is a Windows Only Test";
        }
    }
}

You will then use it like this:

[WindowsOnlyFact]
public void Config_Is_Constructed_Correctly_With_EventLog_On_Windows_Issues()
{
    var settings = ElasticSearchSettings.GetSettings(TestConstants.ConnectionString, "Innova Suiter", "1.0", true);
    var config = LoggerBuilder.GetElasticSearchLogger(settings, _output);
    config.Should().NotBeNull();
    _output.Output.Should().Contain("Applicatiom is not registered as an event source");
}

When I look at my test runner (when running under macOS), I see the following:

If I run the same test under Windows, I get the following:

Here we can see that it ran.

TLDR

We can use an xUnit attribute to designate tests as platform-specific (Windows).

The code is in my GitHub.

Happy hacking!