public void ReplaceTest() { string formatString = "Hello,[Person], you are a good [[job]]"; IDictionary<string, string> replacePattern = new Dictionary<string, string> { {"Person", "John"}, {"job", "student"} }; string expected = "Hello,John, you are a good [student]"; string actual; var target = new NamedFormatterHelper(); actual = target.Replace(formatString, replacePattern); Assert.AreEqual(expected, actual); }