writing a rspec test to add an item to a hash - ruby

Question

I am getting a NoMethodError
for my code but I have defined the add method it says it is missing.
I am trying to add an item to a hash that already exists.
The hash is the dishes and I am trying to use the add method.
The test:
require 'menu'
describe Menu do
it 'has a menu' do
expect(subject.respond_to?(:dishes)).to be true
end
it 'displays dishes and prices' do
expect(subject.dishes).to eq [
{ name: 'Burger', price: 10.95 },
{ name: 'Pizza', price: 14.00 },
{ name: 'Salad', price: 7.60 },
{ name: 'fries', price: 2.90 }
]
end
it 'can add dishes to it' do
menu = Menu.new
menu.add_dish("Icecream", 4.80)
expect(subject.dishes).to eq [
{ name: 'Burger', price: 10.95 },
{ name: 'Pizza', price: 14.00 },
{ name: 'Salad', price: 7.60 },
{ name: 'fries', price: 2.90 },
{ name: 'icecream', price: 4.80 }
]
end
end
the methods
class Menu
def initialize
#dishes = []
end
def dishes
#dishes = [
{ name: 'Burger', price: 10.95 },
{ name: 'Pizza', price: 14.00 },
{ name: 'Salad', price: 7.60 },
{ name: 'fries', price: 2.90 }
]
end
def add_dish(name, price)
#dishes << { name: name, price: price }
end
end
Thank you

Answer 1

The answer of Ryan-Neal Mes solves the NoMethodError, but there are many other problems in your code.
You repeat your self, and you should make your code dry (Don't Repeat Yourself principle)
while you want to add a hash to the list of dishes which is it self a list of hashes, you force the object that needs to call the add method to provide the parameters in a particular order, than the method constructs the hash, so every time you need to call it you need to return to it to see the order of parameters.
the dishes method is wrong, because each time you call it, it assigns the initial array to the #dishes variable. In this case the add_dishes method will have no effect, since the added dish will be deleted the next time you call the dishes method.
your examples are not expressive, so if a test did not pass, you cannot know from the printed messages what's the problem. OK, this is not a big deal in this small example, but in a big application, specs expressiveness is of a higher value.
here the test examples
require 'menu'
describe Menu do
# every time you call the function dishes in an example
# it will be declared and it will return this array
let :dishes do
[
{ name: 'Burger', price: 10.95 },
{ name: 'Pizza', price: 14.00 },
{ name: 'Salad', price: 7.60 },
{ name: 'fries', price: 2.90 }
]
end
# explicit definition of the subject
subject { Menu.new }
# a shorter yet more expressive version of
# expect(subject.respond_to?(:dishes)).to be true
it { is_expected.to respond_to(:dishes) }
# You should always group the examples that test
# the same method
describe '#dishes' do
# it 'displays dishes and prices' do
it 'returns the list of dishes' do
expect(subject.dishes).to eq dishes
end
end
describe "#add_dish" do
# it 'can add dishes to it' do
it "adds the given dish to the list of dishes" do
new_dish = {name: 'salad', price: 4.0 }
expect {
subject.add_dish(new_dish)
}.to change(subject.dishes, :count).by(1)
expect(subject.dishes).to include new_dish
end
end
end
so here is the class definition
class Menu
# you don't need to declare the method dishes
# since this is what attr_reader will do
attr_reader :dishes
def initialize
# this will set the #dishes only once
# but you code #dishes = [...] will return
# the same list every time you call it and
# all the dishes you add through the #add method
# will be deleted.
#dishes = [
{ name: 'Burger', price: 10.95 },
{ name: 'Pizza', price: 14.00 },
{ name: 'Salad', price: 7.60 },
{ name: 'fries', price: 2.90 }
]
end
# dish is a hash {name: '', price: ''}
def add_dish(dish)
#dishes << dish
end
end
so now run rspec --format doc --color and see who expressive are the messages.

Answer 2

It's a bit difficult to get this working without your code, but the problem is pretty straight forward.
Try the edited code below. Note the changes to the spec initialize the menu and add method adds to the instance variable #dishes.
require 'menu'
describe Menu do
it 'displays dishes and prices' do
expect(Menu.new.dishes).to eq [
{ name: 'Burger', price: 10.95 },
{ name: 'Pizza', price: 14.00 },
{ name: 'Salad', price: 7.60 },
{ name: 'fries', price: 2.90 }
]
end
it 'can add dishes to it' do
menu = Menu.new.add("Icecream", 4.80)
expect(menu.dishes).to eq [
{ name: 'Burger', price: 10.95 },
{ name: 'Pizza', price: 14.00 },
{ name: 'Salad', price: 7.60 },
{ name: 'fries', price: 2.90 },
{ name: 'icecream', price: 4.80 }
]
end
end
class Menu
def initialize
#dishes = []
end
def dishes
#dishes ||=
[
{ name: 'Burger', price: 10.95 },
{ name: 'Pizza', price: 14.00 },
{ name: 'Salad', price: 7.60 },
{ name: 'fries', price: 2.90 }
]
end
def add(name, price)
#dishes << { name: name, price: price }
end
end
Hope this helps

Answer 3

It looks like you've got a couple of problems with this code. First, because the add method is not declared as a class method (i.e. def self.add) you can't call it as a class method (as you've seen, Menu.add says NoMethodError). Instead, you'll need to create an instance of the Menu class in your test, perhaps using let:
describe Menu do
let(:menu) { Menu.new }
it 'can add dishes to it' do
menu.add("Icecream", 4.80)
# test your expectations...
end
end
Lastly, as the add method is currently defined, it doesn't modify #dishes but rather just returns a new hash, so your expectation will fail. You'll need to make the add method append the values, perhaps like this:
def add(name, , price)
#dishes << {name: name, price: price}
end

Answer 4

Ah I see your problem. You need to initialize your menu. Add is not a static method. So you need something like,
Menu.new.add(blah, blah)
Look at:
Menu.add("Icecream", 4.80)
This method is wrong. It needs to be:
Menu.new.add("Icecream", 4.80)
or you need something like:
menu = Menu.new
menu.add("Icecream", 4.80)