How to test for (ActiveRecord) object equality

Question

In Ruby 1.9.2 on Rails 3.0.3, I\'m attempting to test for object equality between two Friend (class inherits from ActiveRecord::

Answer 1

If like me you're looking for a Minitest answer to this question then here's a custom method that asserts that the attributes of two objects are equal.

It assumes that you always want to exclude the id, created_at, and updated_at attributes, but you can override that behaviour if you wish.

I like to keep my test_helper.rb clean so created a test/shared/custom_assertions.rb file with the following content.

module CustomAssertions
  def assert_attributes_equal(original, new, except: %i[id created_at updated_at])
    extractor = proc { |record| record.attributes.with_indifferent_access.except(*except) }
    assert_equal extractor.call(original), extractor.call(new)
  end
end

Then alter your test_helper.rb to include it so you can access it within your tests.

require 'shared/custom_assertions'

class ActiveSupport::TestCase
  include CustomAssertions
end

Basic usage:

test 'comments should be equal' do
  assert_attributes_equal(Comment.first, Comment.second)
end

If you want to override the attributes it ignores then pass an array of strings or symbols with the except arg:

test 'comments should be equal' do
  assert_attributes_equal(
    Comment.first, 
    Comment.second, 
    except: %i[id created_at updated_at edited_at]
  )
end