Reject sequence definitions for Active Record primary keys (#419)

Alternative to [thoughtbot/factory_bot#1586][]
Depends on [thoughtbot/factory_bot#1587][]

First, introduce the `FactoryBotRails::FactoryValidator` class to serve
as a generic `factory_bot.compile_factory` event observer.

Throughout the lifecycle of the `FactoryBotRails::Railtie`, afford
various initializers with opportunities to add purpose-built validators
to the instance's internal set.

When `factory_bot.compile_factory` events are published, iterate through
the list of validators and forward along the value of the
[event.payload][] to the validator's `#validate!` method.

Next, introduce the Active Record-specific
`FactoryBotRails::FactoryValidator::ActiveRecordValidator` class. Only
require the module whenever [Active Record's engine is loaded][on_load].

The `ActiveRecordValidator#validate!` method rejects attributes that
define primary key generation logic for `ActiveRecord::Base`
descendants.

In order to test this behavior, add a development dependency on
`sqlite3` and `activerecord`, along with some model and database table
generating helper methods.

[thoughtbot/factory_bot#1586]: thoughtbot/factory_bot#1586
[thoughtbot/factory_bot#1587]: thoughtbot/factory_bot#1587
[event.payload]: module-ActiveSupport::Notifications-label-Subscribers
[on_load]: https://guides.rubyonrails.org/engines.html#avoid-loading-rails-frameworks

Gemfile.lock

@@ -2,7 +2,7 @@ PATH
  remote: .
  specs:
  factory_bot_rails (6.2.0)
- factory_bot (~> 6.2.0)
+ factory_bot (~> 6.3.0)
  railties (>= 5.0.0)
 
 GEM
@@ -21,6 +21,11 @@ GEM
  erubi (~> 1.4)
  rails-dom-testing (~> 2.0)
  rails-html-sanitizer (~> 1.1, >= 1.2.0)
+ activemodel (7.0.4.3)
+ activesupport (= 7.0.4.3)
+ activerecord (7.0.4.3)
+ activemodel (= 7.0.4.3)
+ activesupport (= 7.0.4.3)
  activesupport (7.0.4.3)
  concurrent-ruby (~> 1.0, >= 1.0.2)
  i18n (>= 1.6, < 2)
@@ -69,7 +74,7 @@ GEM
  cucumber-tag-expressions (4.1.0)
  diff-lcs (1.5.0)
  erubi (1.12.0)
- factory_bot (6.2.1)
+ factory_bot (6.3.0)
  activesupport (>= 5.0.0)
  ffi (1.15.5)
  ffi (1.15.5-java)
@@ -150,6 +155,8 @@ GEM
  rubocop (>= 1.7.0, < 2.0)
  rubocop-ast (>= 0.4.0)
  ruby-progressbar (1.13.0)
+ sqlite3 (1.6.2)
+ mini_portile2 (~> 2.8.0)
  standard (1.27.0)
  language_server-protocol (~> 3.17.0.2)
  rubocop (~> 1.50.2)
@@ -167,12 +174,14 @@ PLATFORMS
  ruby
 
 DEPENDENCIES
+ activerecord (>= 5.0.0)
  appraisal
  aruba
  cucumber
  factory_bot_rails!
  rake
  rspec-rails
+ sqlite3
  standard
 
 BUNDLED WITH

README.md

@@ -152,6 +152,22 @@ rails generate factory_bot:model NAME [field:type field:type] [options]
 
 [default factory template]: https://github.com/thoughtbot/factory_bot_rails/tree/master/lib/generators/factory_bot/model/templates/factories.erb
 
+### Active Record Configuration
+
+By default, FactoryBot will refuse to generate Active Record primary key
+columns. Without additional configuration, an Active Record model treats a
+column named `id` as its primary key.
+
+For example, defining an `id` attribute with `add_attribute(:id)`, `id { ... }`,
+or `sequence(:id)` will raise a `FactoryBot::AttributeDefinitionError`.
+
+You can disable this behavior by adding the following to `config/application.rb`
+or the appropriate environment configuration in `config/environments`:
+
+```ruby
+config.factory_bot.reject_primary_key_attributes = false
+```
+
 ## Contributing
 
 Please see [CONTRIBUTING.md](CONTRIBUTING.md).

factory_bot_rails.gemspec

@@ -14,6 +14,9 @@ Gem::Specification.new do |s|
  s.executables = []
  s.license = "MIT"
 
- s.add_runtime_dependency("factory_bot", "~> 6.2.0")
+ s.add_runtime_dependency("factory_bot", "~> 6.3.0")
  s.add_runtime_dependency("railties", ">= 5.0.0")
+
+ s.add_development_dependency("sqlite3")
+ s.add_development_dependency("activerecord", ">= 5.0.0")
 end

lib/factory_bot_rails/factory_validator.rb

@@ -0,0 +1,39 @@
+module FactoryBotRails
+ class FactoryValidator
+ def initialize(validators = [])
+ @validators = Array(validators)
+ end
+
+ def add_validator(validator)
+ @validators << validator
+ end
+
+ def run
+ ActiveSupport::Notifications.subscribe("factory_bot.compile_factory", &validate_compiled_factory)
+ end
+
+ private
+
+ def validate_compiled_factory
+ if Rails.version >= "6.0"
+ rails_6_0_support
+ else
+ rails_5_2_support
+ end
+ end
+
+ def rails_6_0_support
+ proc do |event|
+ @validators.each { |validator| validator.validate!(event.payload) }
+ end
+ end
+
+ def rails_5_2_support
+ proc do |*notification_event_arguments|
+ event = ActiveSupport::Notifications::Event.new(*notification_event_arguments)
+
+ rails_6_0_support.call(event)
+ end
+ end
+ end
+end

lib/factory_bot_rails/factory_validator/active_record_validator.rb

@@ -0,0 +1,18 @@
+module FactoryBotRails
+ class FactoryValidator
+ class ActiveRecordValidator
+ def validate!(payload)
+ attributes, for_class = payload.values_at(:attributes, :class)
+ attributes.each do |attribute|
+ if for_class < ActiveRecord::Base && for_class.primary_key == attribute.name.to_s
+ raise FactoryBot::AttributeDefinitionError, <<~ERROR
+ Attribute generates #{for_class.primary_key.inspect} primary key for #{for_class.name}"
+
+ Do not define #{for_class.primary_key.inspect}. Instead, rely on the database to generate it.
+ ERROR
+ end
+ end
+ end
+ end
+ end
+end

lib/factory_bot_rails/railtie.rb

@@ -3,12 +3,15 @@
 require "factory_bot"
 require "factory_bot_rails/generator"
 require "factory_bot_rails/reloader"
+require "factory_bot_rails/factory_validator"
 require "rails"
 
 module FactoryBotRails
  class Railtie < Rails::Railtie
  config.factory_bot = ActiveSupport::OrderedOptions.new
  config.factory_bot.definition_file_paths = FactoryBot.definition_file_paths
+ config.factory_bot.reject_primary_key_attributes = true
+ config.factory_bot.validator = FactoryBotRails::FactoryValidator.new
 
  initializer "factory_bot.set_fixture_replacement" do
  Generator.new(config).run
@@ -18,9 +21,20 @@ class Railtie < Rails::Railtie
  FactoryBot.definition_file_paths = definition_file_paths
  end
 
+ ActiveSupport.on_load :active_record do
+ config = Rails.configuration.factory_bot
+
+ if config.reject_primary_key_attributes
+ require "factory_bot_rails/factory_validator/active_record_validator"
+
+ config.validator.add_validator FactoryValidator::ActiveRecordValidator.new
+ end
+ end
+
  config.after_initialize do |app|
  FactoryBot.find_definitions
  Reloader.new(app).run
+ app.config.factory_bot.validator.run
  end
 
  private

spec/factory_bot_rails/factory_validator/active_record_validator_spec.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+describe FactoryBotRails::FactoryValidator do
+ before { FactoryBot.reload }
+
+ describe "ActiveRecordValidator" do
+ context "when defined with a class that descends from ActiveRecord::Base" do
+ it "raises an error for a sequence generating its primary key" do
+ define_model "Article", an_id: :integer do
+ self.primary_key = :an_id
+ end
+
+ FactoryBot.define do
+ factory :article do
+ sequence(:an_id)
+ end
+ end
+
+ expect { FactoryBot.create(:article) }
+ .to raise_error(FactoryBot::AttributeDefinitionError)
+ end
+ end
+ end
+end

spec/spec_helper.rb

@@ -5,6 +5,8 @@
 require "factory_bot_rails"
 require "fake_app"
 
+Dir["spec/support/**/*.rb"].each { |f| require File.expand_path(f) }
+
 RSpec.configure do |config|
  config.run_all_when_everything_filtered = true
  config.filter_run :focus

spec/support/macros/define_constant.rb

@@ -0,0 +1,67 @@
+require "active_record"
+
+module DefineConstantMacros
+ def define_class(path, base = Object, &block)
+ const = stub_const(path, Class.new(base))
+ const.class_eval(&block) if block
+ const
+ end
+
+ def define_model(name, columns = {}, &block)
+ model = define_class(name, ActiveRecord::Base, &block)
+ create_table(model.table_name) do |table|
+ columns.each do |column_name, type|
+ table.column column_name, type
+ end
+ end
+ model
+ end
+
+ def create_table(table_name, &block)
+ connection = ActiveRecord::Base.connection
+
+ begin
+ connection.execute("DROP TABLE IF EXISTS #{table_name}")
+ connection.create_table(table_name, &block)
+ created_tables << table_name
+ connection
+ rescue Exception => e # rubocop:disable Lint/RescueException
+ connection.execute("DROP TABLE IF EXISTS #{table_name}")
+ raise e
+ end
+ end
+
+ def clear_generated_tables
+ created_tables.each do |table_name|
+ clear_generated_table(table_name)
+ end
+ created_tables.clear
+ end
+
+ def clear_generated_table(table_name)
+ ActiveRecord::Base
+ .connection
+ .execute("DROP TABLE IF EXISTS #{table_name}")
+ end
+
+ private
+
+ def created_tables
+ @created_tables ||= []
+ end
+end
+
+RSpec.configure do |config|
+ config.include DefineConstantMacros
+
+ config.before(:all) do
+ ActiveRecord::Base.establish_connection(
+ adapter: "sqlite3",
+ database: ":memory:"
+ )
+ end
+
+ config.after do
+ clear_generated_tables
+ end
+end