How to Pass Complex Parameters to Theory-Driven Unit Tests in xUnit?

Passing Complex Parameters to Theory-Driven Unit Tests

Unit testing frameworks like xUnit offer convenient features for data-driven testing. However, when the parameters to the method under test are complex data structures, such as lists of custom classes, the InlineData attribute falls short.

The Theory of Complex Parameters

To tackle this challenge, xUnit provides several options for passing complex parameters to theory-driven unit tests. One such option is the MemberData attribute.

MemberData to the Rescue

The MemberData attribute enables you to specify a property or method that returns IEnumerable. Each object array in this sequence represents the parameters to each test instance. For instance:

[Theory, MemberData(nameof(MyCustomData))]
public void WriteReportsToMemoryStream(...)
{
    // ...
}

public static IEnumerable<object[]> MyCustomData()
{
    // ...
}

ClassData: An Alternative Approach

Prior to xUnit 2.0, another alternative existed: ClassData. Similar to MemberData, ClassData allowed sharing data generators between tests in different classes and namespaces. For example:

public class MyCustomTests
{
    [Theory, ClassData(typeof(MyCustomData))]
    public void WriteReportsToMemoryStream(...)
    {
        // ...
    }
}

public class MyCustomData : IEnumerable<object[]>
{
    // ...
}

MemberData with Static Member Overloading (xUnit >= 2.0)

xUnit 2.0 introduced an overloaded version of MemberData that enables direct use of static members from other classes. The ClassData example above can be rewritten using this overload:

[Theory, MemberData(nameof(MyCustomData.GetData), MemberType = typeof(MyCustomData))]
public void WriteReportsToMemoryStream(...)
{
    // ...
}

Conclusion

These examples illustrate the various ways to pass complex parameters to theory-driven unit tests in xUnit using MemberData, ClassData, and their respective overloads. By leveraging these attributes, developers can conveniently generate data for testing methods that operate on complex data structures.

The above is the detailed content of How to Pass Complex Parameters to Theory-Driven Unit Tests in xUnit?. For more information, please follow other related articles on the PHP Chinese website!