Migrating from NUnit to XUnit–SetupFixture fun

So I was limited to a specific version of NUnit for various reasons, and needed to start being able to run ‘core’ tests, so I migrated to XUnit. Generally not a problem until I hit ‘SetupFixture’. XUnit has no concept of ‘SetupFixture’ and from what I can gather, won’t either (https://github.com/xunit/xunit/issues/111).

So, in order to get the same approach, I need to implement ‘IClassFixture<T>’ on every test class. I could do this by going through each 1 by 1, but then how can I ensure that another developer (or even me!) remembers to do it the next time? For example, creating a new test class. In fact the reason for the SetupFixture was entirely because you can’t assume someone will derive or implement an interface.

In the end, I took the approach of adding another test to my code to ‘test the tests’ ensuring that each test class implemented IClassFixture. The code is below, tweak to your own needs!

[Fact]
public void AllClassesImplementIUseFixture()
{
    var typesWithFactsNotImplementingIClassFixture =
       //Get this assembly and it's types.
        Assembly.GetExecutingAssembly().GetTypes()
        //Get the types with their interfaces and methods
        .Select(type => new {type, interfaces = type.GetInterfaces(), methods = type.GetMethods()})
        //First we only want types where they have a method which is a 'Fact'
        .Where(t => t.methods.Select(Attribute.GetCustomAttributes).Any(attributes => attributes.Any(a => a.GetType() == typeof(FactAttribute))))
        //Then check if that type implements the type
        .Where(t => t.interfaces.All(i => i != typeof(IClassFixture<OriginalSetupFixture>)))
        //Select the name
        .Select(t => t.type.FullName)
        .ToList();

    if (typesWithFactsNotImplementingIClassFixture.Any())
        throw new InvalidOperationException(
            $"All test classes must implement {nameof(IClassFixture<O
riginalSetupFixture>)}{Environment.NewLine}These don't:{Environment.NewLine} * {string.Join($"{Environment.NewLine} * ", typesWithFactsNotImplementingIClassFixture)}");
}

Print | posted @ Wednesday, February 22, 2017 10:00 AM

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