Strange Behaviour with .errors on Factory Girl Stubbed Object - ruby-on-rails-4

Question

I am using factory_girl_rails (4.2.1) and rspec-rails (2.14.0) to test a simple controller on Rails 4. When testing an error case, I use FactoryGirl.build to build an invalid User object. However, the resulting object does not contain any error in #user.errors; yet expect(assigns(:user)).to have(1).errors_on(:email) in the test case still passes. Why doesn't the FactoryGirl generated object has any error, and how does rspec see the error?
Here are the details and code.
The controller simply creates a User object, then redirect to a verification page if creation was successful or render the form again if there is any error.
class RegistrationController < ApplicationController
def new
end
def create
#user = User.create(params.required(:user).permit(:email, :password, :password_confirmation))
if #user.errors.empty?
redirect_to verify_registration_path
else
render :new
end
end
end
In my error case test, I create a User without 'email' using FactoryGirl. It is expected to create an error entry in #user.errors for the 'email' field AND renders the :new template.
describe RegistrationController do
#... Some other examples ...
describe 'GET create' do
def post_create(user_params)
allow(User).to receive(:create).with(ActionController::Parameters.new({user: user_params})[:user]).and_return(FactoryGirl.build(:user, user_params))
post :create, user: user_params
end
context 'without email' do
before { post_create email: '', password: 'testing', password_confirmation: 'testing' }
subject { assigns(:user) }
it 'build the User with error' do
expect(subject).to have(1).errors_on(:email)
end
it 'renders the registration form' do
expect(response).to render_template('new')
end
end
end
end
However, when I ran the test case, only the 'renders the registration form' example failed, but not the other one.
Failures:
1) RegistrationController GET create without email renders the registration form
Failure/Error: expect(response).to render_template('new')
expecting <"new"> but rendering with <[]>
# ./spec/controllers/registration_controller_spec.rb:51:in `block (4 levels) in <top (required)>'
Finished in 0.25726 seconds
6 examples, 1 failure
Failed examples:
rspec ./spec/controllers/registration_controller_spec.rb:50 # RegistrationController GET create without email renders the registration form
What is strange here is that rspec seems to be able to see an error in #user (hence the first test case passes) but for some unknown reason #user.error.empty? returns true in controller causing it to redirect instead of rendering the :new template (hence the failed second test case). I also confirmed in debugger that #user.error was indeed empty.
Is it something wrong with how FactoryGirl handles error, or am I using it wrong?
Thanks

Answer 1

Two things I want to mention here are:
1. Probably You want to use "Post create" instead of "Get create".
2. Whether email is missing or not is the model's concern, not controller's.
I suggest you use stub to return false for the case that email is missing.
The easiest way is:
User.any_instance.stub(:create).and_return(false)
And maybe you want to change some other things in the controller, like "if #user.errors.empty?"
EDIT: Sorry, "create" actually doesn't return false.
So in your controller
#user = User.new(.....)
if #user.save
...
else
render :new
And in your test use
User.any_instance.stub(:save).and_return(false)