public void When_there_is_cookie_Then_setValue_overwrites_cookie()
{
var existingCookie = new HttpCookie("cookie");
existingCookie.Value = "existing value";
existingCookie.Expires = DateTime.Now.AddDays(1);
_httpResponse.Object.Cookies.Add(existingCookie);
DateTime newExpirationDate = DateTime.Now.AddDays(2);
_cookieContainer.SetValue("cookie", "new value", newExpirationDate);
HttpCookie cookie = _httpResponse.Object.Cookies["cookie"];
Assert.That(cookie, Is.Not.Null, "cookie");
Assert.That(cookie.Value, Is.EqualTo("new value"), "cookie value");
Assert.That(cookie.Expires, Is.EqualTo(newExpirationDate), "cookie expiration date");
}