factory girl passing arguments to model definition on build/create - ruby-on-rails

Question

models/message.rb
class Message
attr_reader :bundle_id, :order_id, :order_number, :event
def initialize(message)
hash = message
#bundle_id = hash[:payload][:bundle_id]
#order_id = hash[:payload][:order_id]
#order_number = hash[:payload][:order_number]
#event = hash[:concern]
end
end
spec/models/message_spec.rb
require 'spec_helper'
describe Message do
it 'should save the payload' do
payload = {:payload=>{:order_id=>138251, :order_number=>"AW116554416"}, :concern=>"order_create"}
message = FactoryGirl.build(:message, {:payload=>{:order_id=>138251, :order_number=>"AW116554416"}, :concern=>"order_create"})
message.event.should == "order_create"
end
end
error_log
Failures:
1) Message should save the payload
Failure/Error: message = FactoryGirl.build(:message, {:payload=>{:order_id=>138251, :order_number=>"AW116554416"}, :concern=>"order_create"})
ArgumentError:
wrong number of arguments (0 for 1)
# ./app/models/message.rb:4:in `initialize'
# ./spec/models/message_spec.rb:7:in `block (2 levels) in <top (required)>'

Answer 1

FactoryGirl requires you to define factory first. Let's say in a file spec/factories/messages.rb:
FactoryGirl.define do
factory :message do
bundle_id 1
order_id 2
...etc...
end
end
After this you'll be able to invoke factory build create like this:
FactoryGirl.build(:message) # => bundle_id == 1, order_id == 2
FactoryGirl.build(:message, order_id: 3) # => bundle_id == 1, order_id == 3
However, there is one problem in your particular case. FactoryGirl's default builders operate on top of ActiveRecord-alike interface. It sets defined attributes through setters, not through a hash of attrs passed to the model constructor:
m = Message.new
m.bundle_id = 1
m.order_id = 2
So you have to create a custom constructor to work with the interface of your model (which doesn't conform to ActiveRecord-alike model) and register it in your factory definition. See factory girl docs for details.
Let me show you an example of doing so. Sorry I didn't test it but it should give you a clue:
FactoryGirl.define do
factory :message do
ignore do
# need to make all attributes transient to avoid FactoryGirl calling setters after object initialization
bundle_id 1
order_id 2
end
initialize_with do
new(payload: attributes)
end
end
end

Answer 2

It's because you have a constructor with mandatory arguments. You have a few options;
1) Make the argument non-mandatory (although this would mean you're changing your code to suit your tests - naughty!)
def initialize(message = nil)
2) Use the "initialize_with" syntax in your factory;
describe Message do
it 'should save the payload' do
payload = {:payload=>{:order_id=>138251, :order_number=>"AW116554416"}, :concern=>"order_create"}
message = FactoryGirl.build(:message, {:payload=>{:order_id=>138251, :order_number=>"AW116554416"}, :concern=>"order_create"})
message.event.should == "order_create"
end
initialize_with { new(message) }
end