Need help setting up a method in a feature spec (RSpec)

My program code works as expected, but I need help setting up a method in a feature spec using RSpec (3.1.0) & FactoryGirl. The relevant part of my edit spec is as follows:

require 'rails_helper'

describe "Editing appointments" do

  let!(:appointment) { FactoryGirl.create(:appointment) }

def update_appointment(options={})
  options[:date] ||= "2018-01-02"
  options[:starts_at] ||= "08:00:00"
  options[:ends_at] ||= "10:00:00"
  options[:member_id] ||= 1
  options[:trainer_id] ||= 1

  appointment = options[:appointment]

  visit "/appointments"
  within "#appointment_#{appointment.id}" do
  click_link "Edit"
  #save_and_open_page    
end

  select('2018', :from => 'appointment_date_1i')
  select('December', :from => 'appointment_date_2i')
  select('15', :from => 'appointment_date_3i')
  select('10', :from => 'appointment_starts_at_4i')
  select('00', :from => 'appointment_starts_at_5i')
  select('12', :from => 'appointment_ends_at_4i')
  select('00', :from => 'appointment_ends_at_5i') 

  click_button "Update Appointment"

end

it "updates an appointment successfully with corrected information" do

  update_appointment appointment: appointment,  

    date: '2020-06-11',
    starts_at: '08:00:00',
    ends_at: '10:00:00'                      

  appointment.reload

  expect(page).to have_content ("Appointment was successfully updated.")
  expect(appointment.date).to eq("2020-06-11")    
  expect(appointment.starts_at).to eq("08:00:00")
  expect(appointment.ends_at).to eq("10:00:00")

  end
end

When I run the spec, RSpec generates the following error message:

1) Editing appointments updates an appointment successfully with corrected information
 Failure/Error: expect(appointment.date).to eq("2020-06-11")

   expected: "2020-06-11"
        got: Sat, 15 Dec 2018

   (compared using ==)

   Diff:
   @@ -1,2 +1,2 @@
   -"2020-06-11"
   +Sat, 15 Dec 2018

Looks like the appointment is not being updated with new values. I assume this is caused by how I try to call the "update_appointment" method and/or assign new values. I don't know how best to fix the problem. I'd appreciate any help!