public void Test_Substitute() { var tag = "{this}"; var replacements = new List <string>() { "that", "that other", "and one other" }; var mail = BasicMailBuilder .Substitute(tag, replacements) .Build(); var message = new SendGridMessage(); message.AddSubstitution(tag, replacements); Assert.IsFalse(string.IsNullOrEmpty(message.Header.JsonString())); Assert.AreEqual(message.Header.JsonString(), mail.Header.JsonString()); }