gem "validate_url"

class Pony < ActiveRecord::Base
  # standard validation
  validates :homepage, url: true

  # with allow_nil
  validates :homepage, url: { allow_nil: true }

  # with allow_blank
  validates :homepage, url: { allow_blank: true }

  # without local hostnames
  validates :homepage, url: { no_local: true }

  # with custom schemes
  validates :homepage, url: { schemes: ['https'] }

  # with public suffix database https://publicsuffix.org/
  validates :homepage, url: { public_suffix: true }

  # with Postgres array of urls, described [here](https://guides.rubyonrails.org/active_record_postgresql.html#array)
  validates :homepage, url: { accept_array: true }
end

class Unicorn
  include ActiveModel::Validations

  attr_accessor :homepage

  # with legacy syntax (the syntax above works also)
  validates_url :homepage, allow_blank: true
end

require 'validate_url/rspec_matcher'

RSpec.describe Unicorn
  it { is_expected.to validate_url_of(:homepage) }
end