Rails Unit Test - ruby-on-rails-3

Question

Please help. I am trying to write a unit test for a method in my model. It keeps giving me the following error:
{ 1) Error:
test_Total_for_a_given_date_range_for_Campaigns(LetterTest):
TypeError: can't convert ActiveSupport::Duration into String
c:/Users/Kay/rails-app/CS5942/app/models/letter.rb:19:in +'
c:/Users/Kay/rails-app/CS5942/app/models/letter.rb:19:intribe_total_on'
test/unit/letter_test.rb:17:in `block in '}
This is what i have in my test file:
test "Total for a given date range for Campaigns" do
end_date = (Date.today + 1.day).to_date.strftime('%Y-%m-%d')
expected = Letter.where("letter_campaign_id = '1' and created_at between '#{ (Date.today - 1.day).to_date.strftime('%Y-%m-%d')}' and #{end_date}").count
data = Letter.tribe_total_on( 1 , (Date.today - 1.day).to_date.strftime('%Y-%m-%d') , (Date.today).to_date.strftime('%Y-%m-%d'))
assert_equal expected, data
end
It seems to have a problem with the plus sign. I would be very happy if i could find a solution to it. Thanks.
This is the tribe_total_on method:
def self.tribe_total_on(tribe, start_date, end_date)
#Letter.connection.execute("SELECT COUNT(id) FROM letters WHERE letter_campaign_id = #{tribe} AND created_at BETWEEN '#{start_date.to_date.strftime('%Y-%m-%d')}' and '#{end_date.to_date.strftime('%Y-%m-%d')}'")[0][0]
end_date = end_date + 1.day #This is line 19 ...Had to include the one day to accomodate dates like 2011-06-05 01:02:03
Letter.where("letter_campaign_id = #{tribe} AND created_at between ? and ?", start_date.to_date, end_date.to_date).count
end

Answer 1

Open up Rails console and type in what you're trying to do and you'll get this:
(Date.today).to_date.strftime('%Y-%m-%d') + 1.day
TypeError: can't convert ActiveSupport::Duration into String
from (irb):20:in `+'
You're either going to have to do the conversion to strftime before you pass it to tribe_total_on or you're going to have to add 1.day to the date before you call strftime before you pass it to tribe_total_on.
So:
(Date.today + 1.day).to_date.strftime('%Y-%m-%d')
or:
def self.tribe_total_on(tribe, start_date, end_date)
end_date = (end_date + 1.day).to_date.strftime('%Y-%m-%d')