How to test a custom validator?

Question

I have the following validator:

# Source: http://guides.rubyonrails.org/active_record_validations_callbacks.html#custom-validators # app/validators/email_validator.rb  class EmailValidator < ActiveModel::EachValidator   def validate_each(object, attribute, value)     unless value =~ /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i       object.errors[attribute] << (options[:message] || "is not formatted properly")      end   end end 

I would like to be able to test this in RSpec inside of my lib directory. The problem so far is I am not sure how to initialize an EachValidator.

Answer 1

I am not a huge fan of the other approach because it ties the test too close to the implementation. Also, it's fairly hard to follow. This is the approach I ultimately use. Please keep in mind that this is a gross oversimplification of what my validator actually did... just wanted to demonstrate it more simply. There are definitely optimizations to be made

class OmniauthValidator < ActiveModel::Validator   def validate(record)     if !record.omniauth_provider.nil? && !%w(facebook github).include?(record.omniauth_provider)       record.errors[:omniauth_provider] << 'Invalid omniauth provider'     end   end end 

Associated Spec:

require 'spec_helper'  class Validatable   include ActiveModel::Validations   validates_with OmniauthValidator   attr_accessor  :omniauth_provider end  describe OmniauthValidator do   subject { Validatable.new }    context 'without provider' do     it 'is valid' do       expect(subject).to be_valid     end   end    context 'with valid provider' do     it 'is valid' do       subject.stubs(omniauth_provider: 'facebook')        expect(subject).to be_valid     end   end    context 'with unused provider' do     it 'is invalid' do       subject.stubs(omniauth_provider: 'twitter')        expect(subject).not_to be_valid       expect(subject).to have(1).error_on(:omniauth_provider)     end   end end 

Basically my approach is to create a fake object "Validatable" so that we can actually test the results on it rather than have expectations for each part of the implementation