using System;

using System.Collections.Generic;

using System.Linq;

​

public static class Program

{

    public static void Main()

    {

        List<string> userRoles = new List<string>

        {

            "role1",

            "role2",

            "role3"

        };

        Console.WriteLine(userRoles.IsUserInRole("Role1"));

        Console.WriteLine(userRoles.IsUserInRole("role4"));

    }

}

​

public static class UserRolesExtensions

{

    public static bool IsUserInRole(this IEnumerable<string> roles, string roleName)

    {

        return roles.Any(it => it.Equals(roleName, StringComparison.OrdinalIgnoreCase));

    }

}