Question

I’m trying to create a test case for User model. Basically, it will validate first_name and last_name to be present.

What I am trying to do is to check whether the error on a specific field is empty or not and it should be empty. However it always fails.

What is the correct way to do this?

Here is my code

On my user_spec.rb

require 'spec_helper'

describe User do

  before do
    @user = User.new
  end

  it "must have a first name" do
    @user.errors[:first_name].should_not be_empty
  end

  it "must have a last name" do
    @user.errors[:last_name].should_not be_empty
  end
end

On my user.rb file

class User < ActiveRecord::Base
  validates :first_name, :presence => true
  validates :last_name, :presence => true
end

Answer 1

RSpec supports the notion of an “implicit” subject. If your first argument to the “describe” block is a class, RSpec automatically makes an instance of that class available to your specs. See http://relishapp.com/rspec/rspec-core/v/2-6/dir/subject/implicit-subject.

require 'spec_helper'

describe User do

  it "must have a first name" do    
    subject.should have(1).error_on(:first_name)
  end

  it "must have a last name" do
    subject.should have(1).error_on(:last_name)
  end
end

which results in RSpec output (if using –format documentation) of:

User
  must have a first name
  must have a last name

You can abbreviate it even further if you are content with the RSpec output defaults:

require 'spec_helper'

describe User do
  it { should have(1).error_on(:first_name) }
  it { should have(1).error_on(:last_name) }
end

which results in:

User
  should have 1 error on :first_name
  should have 1 error on :last_name