Create instance of class within another class - ruby

Question

Forgive me if my question isn't completely clear. I have been awake for way too long and I'm feeling a little brain dead.
I'm doing a Ruby exercise and I can't figure out why my rspec test isn't passing for something I thought would work.
require 'date'
class Product
attr_accessor :photo_src, :promotion, :initial_date
attr_reader :default_photo, :default_price, :current_price
def initialize(name, photo, price)
#name = name
#default_photo = photo
#photo_src = photo
#default_price = price
#current_price = price
#initial_date = Date.today.yday
#promotion = false
end
def price_change(sale_price)
calculator = RedPencilCalculator.new(self)
if promotion
if sale_price > #current_price
calculator.end_promotion!
elsif sale_price < (#default_price - (#default_price * 0.3))
calculator.end_promotion!
end
else
calculator.start_promotion!
end
#current_price = sale_price
end
end
class RedPencilCalculator
attr_accessor :promotion_start, :product
def initialize(product)
#product = product
end
def start_promotion!
if start_promotion?
product.promotion = true
product.photo_src = "redX.png"
#promotion_start = Date.today.yday
end
end
#would need to run daily
def end_promotion?
promotion_duration
if #duration == 30 || #duration == 335
end_promotion!
end
end
def end_promotion!
product.promotion = false
product.photo_src = product.default_photo
product.initial_date = Date.today.yday
end
private
def calculate_range
#min_discount = product.default_price - (product.default_price * 0.05)
#max_discount = product.default_price - (product.default_price * 0.3)
end
def start_promotion?
calculate_range
#max_discount <= product.current_price && product.current_price <= #min_discount && Date.today.yday - product.initial_date >= 30
end
def promotion_duration
current_date = Date.today.yday
#duration = current_date - #promotion_start
end
end
Rspec
This doesn't work:
describe Product do
let(:shoes) { Product.new("shoes", "item.png", 100) }
it 'should change the photo_src and promotion attribute if applicable' do
allow(shoes).to receive(:initial_date) { 100 }
shoes.price_change(75)
expect(shoes.promotion).to eq(true)
expect(shoes.photo_src).to eq("redX.png")
end
end
This does:
describe Product do
let(:shoes) { Product.new("shoes", "item.png", 100) }
let(:calculator) { RedPencilCalculator.new(shoes) }
it 'should change the photo_src and promotion attribute if applicable' do
allow(shoes).to receive(:initial_date) { 100 }
shoes.price_change(75)
calculator.start_promotion!
expect(shoes.promotion).to eq(true)
expect(shoes.photo_src).to eq("redX.png")
end
end
So it seems to me that the start_promotion! method call in the price_change method just isn't working.

Answer 1

I don't have a specific answer to your bug but some suggestions on how to pinpoint the problem.
You're testing too much in one unit test. There's so much that can go wrong it's hard (as you've found) to track down where the bug lies. Even if you work it out now, when something changes down the track (as it inevitably will) it will be at least as difficult as it is now to debug.
Simplify the initializer. It should only set #name, #photo, #price. The other instance variables should be methods (write tests unless they're private).
You suspect RedPencilCalculator#start_promotion! has a bug. Write a test to eliminate that possibility.
With more tests in place, the bug will eventually be cornered and crushed!
Lastly - this is easier said than done - but try writing tests first. It is hard but gets easier and even enjoyable!

Answer 2

ok, I put a puts inside of start_promotion? like this:
p "got past calc range: #{#max_discount.inspect} and #{#min_discount.inspect} and #{product.current_price}"
and got:
"got past calc range: 70.0 and 95.0 and 100"
given that the following line checks that current-price is less than the min-discount...
that's the line you've gotta check/fix to make things work