How do I skip specific tests in xUnit based on current platform

XUnit v2.0 is now available. Skippable tests are supported by it directly. Use:

[Fact (Skip = "specific reason")]

I would avoid externalising skipping tests (i.e. a config/command file if it's possible). This somewhat goes against making the tests easy to run and trustworthy. Making the tests ignored in code is the safest approach when other people start to get involved.

I could see a number of options, here are two that involve modification of existing code.

Option 1 - Most intrusive, compile time platform detection

In the VS Solution, define another configuration that defines a precompiler flag MONOWIN (just so that it's explicitly a flag the says that it is for code compiled on Windows for use on Mono).

Then define an attribute that will make the test ignored when compiled for Mono:

public class IgnoreOnMonoFactAttribute : FactAttribute {
#if MONOWIN
    public IgnoreOnMonoFactAttribute() {
        Skip = "Ignored on Mono";
    }
#endif
}

It's actually hard to find any advantages to this method as it involves mocking with the original solution and adds another confiration that needs to be supported.

Option 2 - somewhat intrusive - runtime platform detection

Here is a similar solution to option1, except no separate configuration is required:

public class IgnoreOnMonoFactAttribute : FactAttribute {

    public IgnoreOnMonoFactAttribute() {
        if(IsRunningOnMono()) {
            Skip = "Ignored on Mono";
        }
    }
    /// <summary>
    /// Determine if runtime is Mono.
    /// Taken from http://stackoverflow.com/questions/721161
    /// </summary>
    /// <returns>True if being executed in Mono, false otherwise.</returns>
    public static bool IsRunningOnMono() {
        return Type.GetType("Mono.Runtime") != null;
    }
}

Note 1

xUnit runner will run a method twice if it is marked with [Fact] and [IgnoreOnMonoFact]. (CodeRush doesn't do that, in this case I assume xUnit is correct). This means that any tests methods must have [Fact] replaced with [IgnoreOnMonoFact]

Note 2

CodeRush test runner still ran the [IgnoreOnMonoFact] test, but it did ignore the [Fact(Skip="reason")] test. I assume it is due to CodeRush reflecting xUnit and not actually running it with the aid of xUnit libraries. This works fine with xUnit runner.


There is a new options now.

Add Nuget Package SkippableFact, which allows you to use [SkippableFact] instead of [Fact] and you can use Skip.<xyz> within a Tests to dynamically Skip the Test during runtime.

Example:

[SkippableFact]
public void SomeTestForWindowsOnly()
{
    Skip.IfNot(Environment.IsWindows);

    // Test Windows only functionality.
}

[Fact(Skip="reason")]

works but I prefer to use traits

[Fact, Trait("type","unit")]
public void MyUnitTest(){
  // given 
  // when
  // then
}

[Fact, Trait("type","http")]
public void MyHttpIntegrationTest(){
  // given 
  // when do things over HTTP
  // then
}

usage

dotnet test --filter type=unit

this protects our builds from accidentally running integration tests that devs forgot to skip e.g. [Fact(Skip="Integration")], however it does require unit tests to "opt in" to CI by adding the correct traits which admittedly isn't great.

Tags:

Xunit

Recent Posts