为什么这会抛出一个 System.FormatException

这是string.Format上的错误还是什么？

// Act
string l = "This is an UnitTest embedded resource.";
string r = "Please do not remove or change. Sincerely yours, {0}".FormatWith(model.Username);
string expected = "['r'n't{0}'r'n'r'n'r'n]'r'n{'r'n't'r'n't{1}'r'n'r'n}".FormatWith(l, r);

FormatWith方法只是句法糖的扩展。

public static string FormatWith(this string text, params object[] args)
{
    return string.Format(text, args);
}