Rspec NoMethodError: undefined method `errors_on' - ruby-on-rails

Question

I'm testing for validation of entry of a city attribute in an addresses model. My model spec is as follows
require 'rails_helper'
RSpec.describe Address, :type => :model do
before(:each) do
#valid_attributes = {
street: 'rock avenue',
city: 'MSA',
zip: '00100',
person_id: 1
} # runs before each it block
end
context "Validations" do
it 'must have a city' do
a = Address.new
expect(a.errors_on(:city)).not_to be_empty
end
end
end
When I run the spec, i get the following error
1) Address Validations must have a city
Failure/Error: expect(a.errors_on(:city)).not_to be_empty
NoMethodError:
undefined method `errors_on' for #<Address:0xd844538>
# ./spec/models/address_spec.rb:19:in `block (3 levels) in <top (required)>'
My test gems are set up as following in my Gemfile
group :development, :test do
gem 'rspec-rails'
gem 'factory_girl_rails', :require => false
end
group :test do
gem 'capybara'
gem 'guard'
gem 'guard-rspec'
gem 'libnotify'
gem 'rspec-collection_matchers'
end
I have included the rspec collection matchers in my spec_helper, so I don't understand why I am getting this error
My spec_helper.rb
require 'capybara/rspec'
require 'factory_girl_rails'
require 'rspec/collection_matchers'
However I can see that the method, errors_on has been defined in rspec-collection_matchers gem as shown here
My .rspec
--color
--require spec_helper
I have also changed the position of
require 'rspec/collection_matchers'
to rails_helper.rb, but running the test suite again brings up the same error
rails_helper.rb
ENV["RAILS_ENV"] ||= 'test'
require 'rspec/collection_matchers'
require 'capybara/rspec'
require 'factory_girl_rails'
require 'spec_helper'
require File.expand_path("../../config/environment", __FILE__)
require 'rspec/rails'
Dir[Rails.root.join("spec/support/**/*.rb")].each { |f| require f }
ActiveRecord::Migration.maintain_test_schema!
RSpec.configure do |config|
config.include Capybara::DSL
config.include FactoryGirl::Syntax::Methods
config.fixture_path = "#{::Rails.root}/spec/fixtures"
config.use_transactional_fixtures = true
config.infer_spec_type_from_file_location!
end
My spec_helper.rb is empty with only the block below:
RSpec.configure do |config|
end
I am using Rails 4.1.0, rspec 3.0.0 and rspec-collection_matchers 1.0.0

Answer 1

Without seeing the repo, this is only a guess based on the information. I think this is a load order problem.
It looks like you are loading rspec/collection_matchers in spec_helper, not rails_helper. If you are using the new default configuration, --require spec_helper is in your .rspec file. When you run rspec this will require spec_helper very early on. When that happens it requires rspec/collection_matchers. However, at that point rails_helper has not been loaded. Unfortunately, this also means most of ActiveSupport including ActiveModel are not loaded yet. It also means the Rails autoloading functionality has not been loaded, so those won't get defined when you reference them.
All this to say, the check for ActiveModel here returns false. Which does not load errors_on.
Try moving the require into rails_helper.
Note on testing in isolation:
If you are going for faster testing in isolation this is my suggestion:
spec_helper should be kept very minimal and lightweight, that means for the most part you shouldn't add any require declarations to it
Move the requires you listed from spec_helper into rails_helper, those are mostly Rails specific and do not belong in spec_helper as Rails is not loaded there
If you need access to the other rspec/collection_matchers functionality in specs which do not require Rails, then just add the require 'rspec/collection_matchers' to the top of the spec file; Ruby will handle making sure it is only loaded once