Question

I am fairly new to testing and have a UsersController that I want to test. I am starting with the new action and so far have the following;

require 'spec_helper'

describe UsersController do

  describe "GET 'new'" do
    it "assigns a new User to @user" do
      user = User.new
      get :new
      assigns(:user).should eq(user)
    end
    it "renders the :new template"
  end

end

My UsersController so far looks like this

class UsersController < ApplicationController
  def new
    @user = User.new
  end
end

I expected my first test to work but when I run it I get the following;

Failures:

  1) UsersController GET 'new' assigns a new User to @user
     Failure/Error: assigns(:user).should eq(user)

       expected: #<User id: nil, email: nil, username: nil, password_digest: nil, created_at: nil, updated_at: nil>
            got: #<User id: nil, email: nil, username: nil, password_digest: nil, created_at: nil, updated_at: nil>

       (compared using ==)

       Diff:#<User:0x007fe4bbfceed0>.==(#<User:0x007fe4bce5c290>) returned false even though the diff between #<User:0x007fe4bbfceed0> and #<User:0x007fe4bce5c290> is empty. Check the implementation of #<User:0x007fe4bbfceed0>.==.
     # ./spec/controllers/users_controller_spec.rb:9:in `block (3 levels) in <top (required)>'

Playing around in the console reveals the following;

irb(main):001:0> a = User.new
=> #<User id: nil, email: nil, username: nil, password_digest: nil, created_at: nil, updated_at: nil>
irb(main):002:0> b = User.new
=> #<User id: nil, email: nil, username: nil, password_digest: nil, created_at: nil, updated_at: nil>
irb(main):003:0> a == b
=> false

So now I’m curious as to why 2 empty ActiveRecord objects are not equal (after all, Array.new == Array.new returns true), and what I have to do to make my test pass.

Answer 1

You should probably change your test to something like this:

describe UsersController do

  describe "GET 'new'" do
    it "assigns a new User to @user" do
      get :new
      assigns(:user).should be_new_record
      assigns(:user).kind_of?(User).should be_true
    end
    it "renders the :new template"   end

end

And you will have the same effect. If two objects aren’t saved, they don’t have primary keys to Rails is going to use object_id equality to compare them, that’s why they’re not ==.