[rspec-users] assigns and should eql don't work as expected

David Chelimsky dchelimsky at gmail.com
Sat Jul 17 09:09:46 EDT 2010


On Jul 17, 2010, at 3:29 AM, Daniel Salmeron Amselem wrote:

> Today I've been writing some tests for a new rails 3 app, but after
> reading the doc from http://rdoc.info/projects/rspec/rspec-expectations,
> I still can't understand why the test doesn't work. My setup is:
> 
> rvm 0.1.41
> ruby 1.9.2dev (2010-07-11 revision 28618) [x86_64-darwin10.4.0] ->
> ruby 1.9.2-rc2
> rspec 2.0.0.beta.17
> rspec-rails 2.0.0.beta.17
> devise 1.1.rc2
> 
> This is the test for the controller:
> 
> 
> require 'spec_helper'
> 
> describe PeopleController do
> 
>  describe "routes" do
>    it "should route to GET people#new" do
>      {:get => "/people/new"}.should route_to(:controller =>
> "people", :action => "new")
>    end
>  end
> 
>  describe "Methods" do
> 
>    before :each do
>      @member = Factory(:member)
>      sign_in @member
>      @person = @member.build_person
>    end
> 
>    it "should render form for a new person on GET people#new" do
>      @member.should_receive(:build_person).and_return(@person)
> 
>      get :new
> 
>      assigns[:person].should eql(@person)
>      response.should be_success
>      response.should render_template("new")
>    end
>  end
> 
> end
> 
> And the controller:
> 
> class PeopleController < ApplicationController
>  before_filter :authenticate_member!
> 
>  def new
>    @person = current_member.build_person
>  end
> 
> end
> 
> When running the test I get:
> 
> 
> .F.................
> 
> 1) PeopleController Methods should render form for a new person on GET
> people#new
>    Failure/Error: assigns[:person].should eql(@person)
> 
>    expected #<Person id: nil, first_name: nil, last_name: nil,
> gender: nil, university: nil, year: nil, email: nil, phone: nil,
> house: nil, user_account_id: 126, user_account_type: "Member",
> home_town: nil, bio: nil, current_location: nil, high_school: nil,
> undergrad: nil, profession: nil, concentration: nil, created_at: nil,
> updated_at: nil>
>         got #<Person id: nil, first_name: nil, last_name: nil,
> gender: nil, university: nil, year: nil, email: nil, phone: nil,
> house: nil, user_account_id: 126, user_account_type: "Member",
> home_town: nil, bio: nil, current_location: nil, high_school: nil,
> undergrad: nil, profession: nil, concentration: nil, created_at: nil,
> updated_at: nil>

Here's how ActiveRecord defines == (to which it delegates from eql?)

http://github.com/rails/rails/blob/c6e20586372743ce200449bf0ac21aed04c6b81e/activerecord/lib/active_record/base.rb#L1536

It returns false if the record has no id (!comparison_object.new_record?), even if all of the other attributes match. In order to get this to pass you have to actually save the object so it has an id, not just build it.

I discussed this with Rails core members a year or two ago and while they agreed this would make testing easier, there were two motivating arguments not to change it: a) conceptually, id-less records are not necessarily the same entity (this one is a bit fuzzy to me) and b) it's a risky change given the amount of rails code in existence.

The other thing you can do is skip the stubbing and just say: 

  assigns(:person).should be_a_new(Person)

You could also write a custom matcher - something like match_new_record(other) that compares all of the attributes. Maybe it's have_same_attributes_as:

  assigns(:person).should have_same_attributes_as(@person)

I'd consider adding that to rspec-rails. Might be good to have a matcher with docs that explain all this to help avoid this sort of confusion in the future.

WDYT?,
David


> 
>    (compared using eql?)
>    # ./spec/controllers/people_controller_spec.rb:24:in `block (3
> levels) in <top (required)>'
> 
> 
> Finished in 2.29 seconds
> 19 examples, 1 failure
> 
> The error with the full backtrace here: http://gist.github.com/479362
> 
> Which doesn't seem to make sense. Any ideas?
> 
> Thanks.
> _______________________________________________
> rspec-users mailing list
> rspec-users at rubyforge.org
> http://rubyforge.org/mailman/listinfo/rspec-users



More information about the rspec-users mailing list