CODEWITHSUNDEEP
c#xunitxunit.net
Adam
Adam

Reputation: 1159

XUnit - Mixing theory data mechanisms, input and expected data

When creating Theory test cases with XUnit I would like to be able to include both the parameters and the expected outcome for each case. I have used the InlineData attribute but for heavy configuration loading this is less than optimal and does not permit reuse. 

[InlineData(1,2,3,4,5,6,7,...)]

As such I have moved the test configurations out to a separate class and now load them with MemberData and MemberType. 

[Theory]
[MemberData(nameof(DataClass.Data), MemberType = typeof(DataClass))]
public void TestValidConfig(Configuration config)
{
    ...
}

However this does not allow me to specify the expected outcome like i could if using a basic tag i.e.

[InlineData("Input1", "Input2", "Input3", "ExpectedResult")]

I don't want to include the expected outcome with the configuration data as this will be reused in multiple tests.

Has anyone got a solution to this challenge?

So the underlying challenge is having complex test data, that could be used in multiple places, but then wanting to separate the expected outcome. So in a calculator (bad example) you could have lists of numbers that are the test data. These could then be passed into an add or multiply or subtraction test. This is where I would want to separate the input and the expected output data.

Upvotes: 0

Views: 1583

Answers (1)

kovac
kovac

Reputation: 5389

Here's a suggestion:

  1. Create a class to generate test data:
    internal static class TestData
    {
        public static IList<T> Get<T>(int count = 10)
        {
            // I'm using NBuilder here to generate test data quickly.
            // Use your own logic to create your test data.
            return Builder<T>.CreateListOfSize(count).Build();
        }
    }

Now, all your test classes can leverage this to get the same set of test data. So, in your data class, you would do something along the lines of

public class DataClass
{
    public static IEnumerable<object[]> Data()
    {
         return new List<object[]>
                {
                    new object[] { TestData.Get(), this.ExpectedResult() }
                };
    }
}

Now you can follow through with your original approach:

[Theory]
[MemberData(nameof(DataClass.Data), MemberType = typeof(DataClass))]
public void TestValidConfig(Data input, Configuration expected)
{
    ...
}

If your tests don't mutate the input data, You can collect them into a fixture and inject the input data through constructor. This would speed up the tests since you don't have to generate the input data per test. Check out shared context for more information.

Upvotes: 1

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