public void And_setting_exists_Then_existing_setting_should_be_replaced()
{
var settings = new AppSettings("NonExistingFile", FileOption.None);
var settingName = "setting";
// Original value
settings.SetValue(settingName, "a");
Assert.AreEqual("a", settings.GetValue(settingName));
// Save with different value
settings.SetValue(settingName, "b");
Assert.AreEqual("b", settings.GetValue(settingName));
}