postgres_unique_constraint_matcher.rb

require 'rspec/expectations'

=begin
  # Example use case in a test suite:
  # Make sure to have defined a factory in factory-bot for "job_application"
  describe JobApplication, type: :model do
    it { is_expected.to enforce_uniqueness_of(:uuid) }
  end
=end

RSpec::Matchers.define :enforce_uniqueness_of do |attribute|
  # Quick and easy way to make sure that a unique index has been added to the field
  # we bypass the ActiveRecord validations when saving the model and check that the
  # database throws an error

  match do |model|
    factory_name = model.class.name.underscore
    duplicate_value = SecureRandom.uuid

    model_a = create(factory_name, attribute.to_sym => duplicate_value)
    model_b = build(factory_name, attribute.to_sym => duplicate_value)

    begin
      model_b.save(validate: false)
      false
    rescue PG::UniqueViolation, ActiveRecord::RecordNotUnique => e
      true
    end
  end
end