SimplerConvention.cs

public class CustomConvention : Convention
{
    public CustomConvention()
    {
        Classes
            .NameEndsWith("Tests");

        Methods
            .Where(method => method.IsVoid());

        Parameters(FindInputs);
    }

    private static IEnumerable<object[]> FindInputs(MethodInfo method)
    {
        var parameters = method.GetParameters();

        if (parameters.Length == 1)
        {
            var testClass = method.ReflectedType;
            var parameterType = parameters.Single().ParameterType;

            var enumerableOfParameterType = typeof(IEnumerable<>).MakeGenericType(parameterType);

            var sources = testClass.GetMethods(BindingFlags.Static | BindingFlags.Public)
                                   .Where(m => !m.GetParameters().Any())
                                   .Where(m => m.ReturnType == enumerableOfParameterType)
                                   .ToArray();

            foreach (var source in sources)
                foreach (var input in (IEnumerable)source.Invoke(null, null))
                    yield return new[] { input };
        }
    }
}