如何为此类中的方法编写单元测试

示例类中，如何为像 derov 这样的方法编写单元测试？我想举一个示例来说明如何在代码中编写测试用例，以测试只有大字母的字符串输入是否会按我预期给出结果。

编辑：我自己通过编写一个测试用例来解决这个问题，例如下面类上方发布的测试用例。

   ///If the expected result and the res variable is equal then the test case has not detected a   fault.
   [TestCase]
    public void TestStringWithOnlyBigConsonantsDerov()
    {
  //declare a string res = classname.methodname("string"); 
        string res = rovar.derov("BOBCOCFOFGOGHOHJOJKOKLOL")
  //check if equal ("expected result", variable holding real result)
        Assert.AreEqual("BCFGHJKL", res); 
    }
class CodeToTest
{
    static class danish
    {
        static string lower_consonants = "bcdghjklmnpqrstvwxz";
        static string upper_consonants = "BCFGHJKLMNPQRSTVWXZ";
        /// <summary>
        /// Encode the string to danish.
        /// Normal is a parameter that contains text which a user types in and 
        /// which shall be translated into danish. 
        /// </summary>
        /// <param name="normal">Normal string.</param>
        /// <returns>Encoded string.</returns>
        public static string danish(string normal)
        {
            if (normal == null) 
                return null;
            System.Text.StringBuilder builder = new System.Text.StringBuilder();
            foreach (char c in normal)
                if (lower_consonants.Contains(c.ToString()))
                    builder.Append(c + "o" + c);

                else if (upper_consonants.Contains(c.ToString())) 
                    builder.Append(c + "O" + c);
                else
                    builder.Append(c);
            return builder.ToString();
        }
        /// <summary>
        /// Decode a string from danish.
        /// </summary>
        /// <param name="dan">Encoded string.</param>
        /// <returns>Normal string.</returns>
        public static string derov(string dan)
        {
            if (dan == null)
                return null;
            foreach (char c in lower_consonants)
                dan = dan.Replace(c + "o" + c, c.ToString());
            foreach (char c in upper_consonants)
                dan = dan.Replace(c + "O" + c, c.ToString());
            return dan;
        }
    }
}

}