fixtures.rb

# frozen_string_literal: true

require "erb"
require "yaml"
require "zlib"
require "set"
require "active_support/dependencies"
require "active_support/core_ext/digest/uuid"
require "active_record/test_fixtures"

module ActiveRecord
  class FixtureClassNotFound < ActiveRecord::ActiveRecordError # :nodoc:
  end

  # = Active Record \Fixtures
  #
  # \Fixtures are a way of organizing data that you want to test against; in short, sample data.
  #
  # They are stored in YAML files, one file per model, which are by default placed in either
  # <tt><your-rails-app>/test/fixtures/</tt> or in the <tt>test/fixtures</tt>
  # folder under any of your application's engines.
  #
  # The location can also be changed with ActiveSupport::TestCase.fixture_paths=,
  # once you have <tt>require "rails/test_help"</tt> in your +test_helper.rb+.
  #
  # The fixture file ends with the +.yml+ file extension, for example:
  # <tt><your-rails-app>/test/fixtures/web_sites.yml</tt>).
  #
  # The format of a fixture file looks like this:
  #
  #   rubyonrails:
  #     id: 1
  #     name: Ruby on Rails
  #     url: http://www.rubyonrails.org
  #
  #   google:
  #     id: 2
  #     name: Google
  #     url: http://www.google.com
  #
  # This fixture file includes two fixtures. Each YAML fixture (i.e. record) is given a name and
  # is followed by an indented list of key/value pairs in the "key: value" format. Records are
  # separated by a blank line for your viewing pleasure.
  #
  # == Ordering
  #
  # Fixtures by default are unordered. This is because the maps in YAML are unordered.
  #
  # If you want ordered fixtures, use the omap YAML type.
  # See https://yaml.org/type/omap.html for the specification.
  #
  # You will need ordered fixtures when you have foreign key constraints
  # on keys in the same table. This is commonly needed for tree structures.
  #
  # For example:
  #
  #    --- !omap
  #    - parent:
  #        id:         1
  #        parent_id:  NULL
  #        title:      Parent
  #    - child:
  #        id:         2
  #        parent_id:  1
  #        title:      Child
  #
  # == Using Fixtures in Test Cases
  #
  # Since fixtures are a testing construct, we use them in our unit and functional tests. There
  # are two ways to use the fixtures, but first let's take a look at a sample unit test:
  #
  #   require "test_helper"
  #
  #   class WebSiteTest < ActiveSupport::TestCase
  #     test "web_site_count" do
  #       assert_equal 2, WebSite.count
  #     end
  #   end
  #
  # By default, +test_helper.rb+ will load all of your fixtures into your test
  # database, so this test will succeed.
  #
  # The testing environment will automatically load all the fixtures into the database before each
  # test. To ensure consistent data, the environment deletes the fixtures before running the load.
  #
  # In addition to being available in the database, the fixture's data may also be accessed by
  # using a special dynamic method, which has the same name as the model.
  #
  # Passing in a fixture name to this dynamic method returns the fixture matching this name:
  #
  #   test "find one" do
  #     assert_equal "Ruby on Rails", web_sites(:rubyonrails).name
  #   end
  #
  # Passing in multiple fixture names returns all fixtures matching these names:
  #
  #   test "find all by name" do
  #     assert_equal 2, web_sites(:rubyonrails, :google).length
  #   end
  #
  # Passing in no arguments returns all fixtures:
  #
  #   test "find all" do
  #     assert_equal 2, web_sites.length
  #   end
  #
  # Passing in any fixture name that does not exist will raise <tt>StandardError</tt>:
  #
  #   test "find by name that does not exist" do
  #     assert_raise(StandardError) { web_sites(:reddit) }
  #   end
  #
  # Alternatively, you may enable auto-instantiation of the fixture data. For instance, take the
  # following tests:
  #
  #   test "find_alt_method_1" do
  #     assert_equal "Ruby on Rails", @web_sites['rubyonrails']['name']
  #   end
  #
  #   test "find_alt_method_2" do
  #     assert_equal "Ruby on Rails", @rubyonrails.name
  #   end
  #
  # In order to use these methods to access fixtured data within your test cases, you must specify one of the
  # following in your ActiveSupport::TestCase-derived class:
  #
  # - to fully enable instantiated fixtures (enable alternate methods #1 and #2 above)
  #     self.use_instantiated_fixtures = true
  #
  # - create only the hash for the fixtures, do not 'find' each instance (enable alternate method #1 only)
  #     self.use_instantiated_fixtures = :no_instances
  #
  # Using either of these alternate methods incurs a performance hit, as the fixtured data must be fully
  # traversed in the database to create the fixture hash and/or instance variables. This is expensive for
  # large sets of fixtured data.
  #
  # == Dynamic fixtures with \ERB
  #
  # Sometimes you don't care about the content of the fixtures as much as you care about the volume.
  # In these cases, you can mix ERB in with your YAML fixtures to create a bunch of fixtures for load
  # testing, like:
  #
  #   <% 1.upto(1000) do |i| %>
  #   fix_<%= i %>:
  #     id: <%= i %>
  #     name: guy_<%= i %>
  #   <% end %>
  #
  # This will create 1000 very simple fixtures.
  #
  # Using ERB, you can also inject dynamic values into your fixtures with inserts like
  # <tt><%= Date.today.strftime("%Y-%m-%d") %></tt>.
  # This is however a feature to be used with some caution. The point of fixtures are that they're
  # stable units of predictable sample data. If you feel that you need to inject dynamic values, then
  # perhaps you should reexamine whether your application is properly testable. Hence, dynamic values
  # in fixtures are to be considered a code smell.
  #
  # Helper methods defined in a fixture will not be available in other fixtures, to prevent against
  # unwanted inter-test dependencies. Methods used by multiple fixtures should be defined in a module
  # that is included in ActiveRecord::FixtureSet.context_class.
  #
  # - define a helper method in <tt>test_helper.rb</tt>
  #     module FixtureFileHelpers
  #       def file_sha(path)
  #         OpenSSL::Digest::SHA256.hexdigest(File.read(Rails.root.join('test/fixtures', path)))
  #       end
  #     end
  #     ActiveRecord::FixtureSet.context_class.include FixtureFileHelpers
  #
  # - use the helper method in a fixture
  #     photo:
  #       name: kitten.png
  #       sha: <%= file_sha 'files/kitten.png' %>
  #
  # == Transactional Tests
  #
  # Test cases can use begin+rollback to isolate their changes to the database instead of having to
  # delete+insert for every test case.
  #
  #   class FooTest < ActiveSupport::TestCase
  #     self.use_transactional_tests = true
  #
  #     test "godzilla" do
  #       assert_not_empty Foo.all
  #       Foo.destroy_all
  #       assert_empty Foo.all
  #     end
  #
  #     test "godzilla aftermath" do
  #       assert_not_empty Foo.all
  #     end
  #   end
  #
  # If you preload your test database with all fixture data (probably by running <tt>bin/rails db:fixtures:load</tt>)
  # and use transactional tests, then you may omit all fixtures declarations in your test cases since
  # all the data's already there and every case rolls back its changes.
  #
  # In order to use instantiated fixtures with preloaded data, set +self.pre_loaded_fixtures+ to
  # true. This will provide access to fixture data for every table that has been loaded through
  # fixtures (depending on the value of +use_instantiated_fixtures+).
  #
  # When *not* to use transactional tests:
  #
  # 1. You're testing whether a transaction works correctly. Nested transactions don't commit until
  #    all parent transactions commit, particularly, the fixtures transaction which is begun in setup
  #    and rolled back in teardown. Thus, you won't be able to verify
  #    the results of your transaction until Active Record supports nested transactions or savepoints (in progress).
  # 2. Your database does not support transactions. Every Active Record database supports transactions except MySQL MyISAM.
  #    Use InnoDB, MaxDB, or NDB instead.
  #
  # == Advanced Fixtures
  #
  # Fixtures that don't specify an ID get some extra features:
  #
  # * Stable, autogenerated IDs
  # * Label references for associations (belongs_to, has_one, has_many)
  # * HABTM associations as inline lists
  #
  # There are some more advanced features available even if the id is specified:
  #
  # * Autofilled timestamp columns
  # * Fixture label interpolation
  # * Support for YAML defaults
  #
  # === Stable, Autogenerated IDs
  #
  # Here, have a monkey fixture:
  #
  #   george:
  #     id: 1
  #     name: George the Monkey
  #
  #   reginald:
  #     id: 2
  #     name: Reginald the Pirate
  #
  # Each of these fixtures has two unique identifiers: one for the database
  # and one for the humans. Why don't we generate the primary key instead?
  # Hashing each fixture's label yields a consistent ID:
  #
  #   george: # generated id: 503576764
  #     name: George the Monkey
  #
  #   reginald: # generated id: 324201669
  #     name: Reginald the Pirate
  #
  # Active Record looks at the fixture's model class, discovers the correct
  # primary key, and generates it right before inserting the fixture
  # into the database.
  #
  # The generated ID for a given label is constant, so we can discover
  # any fixture's ID without loading anything, as long as we know the label.
  #
  # === Label references for associations (+belongs_to+, +has_one+, +has_many+)
  #
  # Specifying foreign keys in fixtures can be very fragile, not to
  # mention difficult to read. Since Active Record can figure out the ID of
  # any fixture from its label, you can specify FK's by label instead of ID.
  #
  # ==== +belongs_to+
  #
  # Let's break out some more monkeys and pirates.
  #
  #   ### in pirates.yml
  #
  #   reginald:
  #     id: 1
  #     name: Reginald the Pirate
  #     monkey_id: 1
  #
  # <code></code>
  #
  #   ### in monkeys.yml
  #
  #   george:
  #     id: 1
  #     name: George the Monkey
  #     pirate_id: 1
  #
  # Add a few more monkeys and pirates and break this into multiple files,
  # and it gets pretty hard to keep track of what's going on. Let's
  # use labels instead of IDs:
  #
  #   ### in pirates.yml
  #
  #   reginald:
  #     name: Reginald the Pirate
  #     monkey: george
  #
  # <code></code>
  #
  #   ### in monkeys.yml
  #
  #   george:
  #     name: George the Monkey
  #     pirate: reginald
  #
  # Pow! All is made clear. Active Record reflects on the fixture's model class,
  # finds all the +belongs_to+ associations, and allows you to specify
  # a target *label* for the *association* (monkey: george) rather than
  # a target *id* for the *FK* (<tt>monkey_id: 1</tt>).
  #
  # ==== Polymorphic +belongs_to+
  #
  # Supporting polymorphic relationships is a little bit more complicated, since
  # Active Record needs to know what type your association is pointing at. Something
  # like this should look familiar:
  #
  #   ### in fruit.rb
  #
  #   belongs_to :eater, polymorphic: true
  #
  # <code></code>
  #
  #   ### in fruits.yml
  #
  #   apple:
  #     id: 1
  #     name: apple
  #     eater_id: 1
  #     eater_type: Monkey
  #
  # Can we do better? You bet!
  #
  #   apple:
  #     eater: george (Monkey)
  #
  # Just provide the polymorphic target type and Active Record will take care of the rest.
  #
  # ==== +has_and_belongs_to_many+ or <tt>has_many :through</tt>
  #
  # \Time to give our monkey some fruit.
  #
  #   ### in monkeys.yml
  #
  #   george:
  #     id: 1
  #     name: George the Monkey
  #
  # <code></code>
  #
  #   ### in fruits.yml
  #
  #   apple:
  #     id: 1
  #     name: apple
  #
  #   orange:
  #     id: 2
  #     name: orange
  #
  #   grape:
  #     id: 3
  #     name: grape
  #
  # <code></code>
  #
  #   ### in fruits_monkeys.yml
  #
  #   apple_george:
  #     fruit_id: 1
  #     monkey_id: 1
  #
  #   orange_george:
  #     fruit_id: 2
  #     monkey_id: 1
  #
  #   grape_george:
  #     fruit_id: 3
  #     monkey_id: 1
  #
  # Let's make the HABTM fixture go away.
  #
  #   ### in monkeys.yml
  #
  #   george:
  #     id: 1
  #     name: George the Monkey
  #     fruits: apple, orange, grape
  #
  # <code></code>
  #
  #   ### in fruits.yml
  #
  #   apple:
  #     name: apple
  #
  #   orange:
  #     name: orange
  #
  #   grape:
  #     name: grape
  #
  # Zap! No more fruits_monkeys.yml file. We've specified the list of fruits
  # on George's fixture, but we could've just as easily specified a list
  # of monkeys on each fruit. As with +belongs_to+, Active Record reflects on
  # the fixture's model class and discovers the +has_and_belongs_to_many+
  # associations.
  #
  # === Autofilled \Timestamp Columns
  #
  # If your table/model specifies any of Active Record's
  # standard timestamp columns (+created_at+, +created_on+, +updated_at+, +updated_on+),
  # they will automatically be set to <tt>Time.now</tt>.
  #
  # If you've set specific values, they'll be left alone.
  #
  # === Fixture label interpolation
  #
  # The label of the current fixture is always available as a column value:
  #
  #   geeksomnia:
  #     name: Geeksomnia's Account
  #     subdomain: $LABEL
  #     email: $LABEL@email.com
  #
  # Also, sometimes (like when porting older join table fixtures) you'll need
  # to be able to get a hold of the identifier for a given label. ERB
  # to the rescue:
  #
  #   george_reginald:
  #     monkey_id: <%= ActiveRecord::FixtureSet.identify(:reginald) %>
  #     pirate_id: <%= ActiveRecord::FixtureSet.identify(:george) %>
  #
  # If the model uses UUID values for identifiers, add the +:uuid+ argument:
  #
  #   ActiveRecord::FixtureSet.identify(:boaty_mcboatface, :uuid)
  #
  # === Support for YAML defaults
  #
  # You can set and reuse defaults in your fixtures YAML file.
  # This is the same technique used in the +database.yml+ file to specify
  # defaults:
  #
  #   DEFAULTS: &DEFAULTS
  #     created_on: <%= 3.weeks.ago.to_fs(:db) %>
  #
  #   first:
  #     name: Smurf
  #     <<: *DEFAULTS
  #
  #   second:
  #     name: Fraggle
  #     <<: *DEFAULTS
  #
  # Any fixture labeled "DEFAULTS" is safely ignored.
  #
  # Besides using "DEFAULTS", you can also specify what fixtures will
  # be ignored by setting "ignore" in "_fixture" section.
  #
  #   # users.yml
  #   _fixture:
  #     ignore:
  #       - base
  #     # or use "ignore: base" when there is only one fixture that needs to be ignored.
  #
  #   base: &base
  #     admin: false
  #     introduction: "This is a default description"
  #
  #   admin:
  #     <<: *base
  #     admin: true
  #
  #   visitor:
  #     <<: *base
  #
  # In the above example, 'base' will be ignored when creating fixtures.
  # This can be used for common attributes inheriting.
  #
  # == Composite Primary Key Fixtures
  #
  # Fixtures for composite primary key tables are fairly similar to normal tables.
  # When using an id column, the column may be omitted as usual:
  #
  #   # app/models/book.rb
  #   class Book < ApplicationRecord
  #     self.primary_key = [:author_id, :id]
  #     belongs_to :author
  #   end
  #
  # <code></code>
  #
  #   # books.yml
  #   alices_adventure_in_wonderland:
  #     author_id: <%= ActiveRecord::FixtureSet.identify(:lewis_carroll) %>
  #     title: "Alice's Adventures in Wonderland"
  #
  # However, in order to support composite primary key relationships,
  # you must use the `composite_identify` method:
  #
  #   # app/models/book_orders.rb
  #   class BookOrder < ApplicationRecord
  #     self.primary_key = [:shop_id, :id]
  #     belongs_to :order, query_constraints: [:shop_id, :order_id]
  #     belongs_to :book, query_constraints: [:author_id, :book_id]
  #   end
  #
  # <code></code>
  #
  #   # book_orders.yml
  #   alices_adventure_in_wonderland_in_books:
  #     author: lewis_carroll
  #     book_id: <%= ActiveRecord::FixtureSet.composite_identify(
  #                  :alices_adventure_in_wonderland, Book.primary_key)[:id] %>
  #     shop: book_store
  #     order_id: <%= ActiveRecord::FixtureSet.composite_identify(
  #                  :books, Order.primary_key)[:id] %>
  #
  # == Configure the fixture model class
  #
  # It's possible to set the fixture's model class directly in the YAML file.
  # This is helpful when fixtures are loaded outside tests and
  # +set_fixture_class+ is not available (e.g.
  # when running <tt>bin/rails db:fixtures:load</tt>).
  #
  #   _fixture:
  #     model_class: User
  #   david:
  #     name: David
  #
  # Any fixtures labeled "_fixture" are safely ignored.
  class FixtureSet
    require "active_record/fixture_set/file"
    require "active_record/fixture_set/render_context"
    require "active_record/fixture_set/table_rows"

    #--
    # An instance of FixtureSet is normally stored in a single YAML file and
    # possibly in a folder with the same name.
    #++

    MAX_ID = 2**30 - 1

    @@all_cached_fixtures = Hash.new { |h, k| h[k] = {} }

    cattr_accessor :all_loaded_fixtures, default: {}

    class << self
      def default_fixture_model_name(fixture_set_name, config = ActiveRecord::Base) # :nodoc:
        config.pluralize_table_names ?
          fixture_set_name.singularize.camelize :
          fixture_set_name.camelize
      end

      def default_fixture_table_name(fixture_set_name, config = ActiveRecord::Base) # :nodoc:
        "#{ config.table_name_prefix }"\
        "#{ fixture_set_name.tr('/', '_') }"\
        "#{ config.table_name_suffix }".to_sym
      end

      def reset_cache
        @@all_cached_fixtures.clear
      end

      def cache_for_connection(connection)
        @@all_cached_fixtures[connection]
      end

      def fixture_is_cached?(connection, table_name)
        cache_for_connection(connection)[table_name]
      end

      def cached_fixtures(connection, keys_to_fetch = nil)
        if keys_to_fetch
          cache_for_connection(connection).values_at(*keys_to_fetch)
        else
          cache_for_connection(connection).values
        end
      end

      def cache_fixtures(connection, fixtures_map)
        cache_for_connection(connection).update(fixtures_map)
      end

      def instantiate_fixtures(object, fixture_set, load_instances = true)
        return unless load_instances
        fixture_set.each do |fixture_name, fixture|
          object.instance_variable_set "@#{fixture_name}", fixture.find
        rescue FixtureClassNotFound
          nil
        end
      end

      def instantiate_all_loaded_fixtures(object, load_instances = true)
        all_loaded_fixtures.each_value do |fixture_set|
          instantiate_fixtures(object, fixture_set, load_instances)
        end
      end

      def create_fixtures(fixtures_directories, fixture_set_names, class_names = {}, config = ActiveRecord::Base, &block)
        fixture_set_names = Array(fixture_set_names).map(&:to_s)
        class_names.stringify_keys!

        # FIXME: Apparently JK uses this.
        connection = block_given? ? block : lambda { ActiveRecord::Base.connection }

        fixture_files_to_read = fixture_set_names.reject do |fs_name|
          fixture_is_cached?(connection.call, fs_name)
        end

        if fixture_files_to_read.any?
          fixtures_map = read_and_insert(
            Array(fixtures_directories),
            fixture_files_to_read,
            class_names,
            connection,
          )
          cache_fixtures(connection.call, fixtures_map)
        end
        cached_fixtures(connection.call, fixture_set_names)
      end

      # Returns a consistent, platform-independent identifier for +label+.
      #
      # \Integer identifiers are values less than 2^30. UUIDs are RFC 4122 version 5 SHA-1 hashes.
      def identify(label, column_type = :integer)
        if column_type == :uuid
          Digest::UUID.uuid_v5(Digest::UUID::OID_NAMESPACE, label.to_s)
        else
          Zlib.crc32(label.to_s) % MAX_ID
        end
      end

      # Returns a consistent, platform-independent hash representing a mapping
      # between the label and the subcomponents of the provided composite key.
      #
      # Example:
      #
      #   composite_identify("label", [:a, :b, :c]) # => { a: hash_1, b: hash_2, c: hash_3 }
      def composite_identify(label, key)
        key
          .index_with
          .with_index { |sub_key, index| (identify(label) << index) % MAX_ID }
          .with_indifferent_access
      end

      # Superclass for the evaluation contexts used by \ERB fixtures.
      def context_class
        @context_class ||= Class.new
      end

      private
        def read_and_insert(fixtures_directories, fixture_files, class_names, connection) # :nodoc:
          fixtures_map = {}
          directory_glob = "{#{fixtures_directories.join(",")}}"
          fixture_sets = fixture_files.map do |fixture_set_name|
            klass = class_names[fixture_set_name]
            fixtures_map[fixture_set_name] = new( # ActiveRecord::FixtureSet.new
              nil,
              fixture_set_name,
              klass,
              ::File.join(directory_glob, fixture_set_name)
            )
          end
          update_all_loaded_fixtures(fixtures_map)

          insert(fixture_sets, connection)

          fixtures_map
        end

        def insert(fixture_sets, connection) # :nodoc:
          fixture_sets_by_connection = fixture_sets.group_by do |fixture_set|
            if fixture_set.model_class
              fixture_set.model_class.connection
            else
              connection.call
            end
          end

          fixture_sets_by_connection.each do |conn, set|
            table_rows_for_connection = Hash.new { |h, k| h[k] = [] }

            set.each do |fixture_set|
              fixture_set.table_rows.each do |table, rows|
                table_rows_for_connection[table].unshift(*rows)
              end
            end

            conn.insert_fixtures_set(table_rows_for_connection, table_rows_for_connection.keys)

            check_all_foreign_keys_valid!(conn)

            # Cap primary key sequences to max(pk).
            if conn.respond_to?(:reset_pk_sequence!)
              set.each { |fs| conn.reset_pk_sequence!(fs.table_name) }
            end
          end
        end

        def check_all_foreign_keys_valid!(conn)
          return unless ActiveRecord.verify_foreign_keys_for_fixtures

          begin
            conn.check_all_foreign_keys_valid!
          rescue ActiveRecord::StatementInvalid => e
            raise "Foreign key violations found in your fixture data. Ensure you aren't referring to labels that don't exist on associations. Error from database:\n\n#{e.message}"
          end
        end

        def update_all_loaded_fixtures(fixtures_map) # :nodoc:
          all_loaded_fixtures.update(fixtures_map)
        end
    end

    attr_reader :table_name, :name, :fixtures, :model_class, :ignored_fixtures, :config

    def initialize(_, name, class_name, path, config = ActiveRecord::Base)
      @name     = name
      @path     = path
      @config   = config

      self.model_class = class_name
      @fixtures = read_fixture_files(path)

      @table_name = model_class&.table_name || self.class.default_fixture_table_name(name, config)
    end

    def [](x)
      fixtures[x]
    end

    def []=(k, v)
      fixtures[k] = v
    end

    def each(&block)
      fixtures.each(&block)
    end

    def size
      fixtures.size
    end

    # Returns a hash of rows to be inserted. The key is the table, the value is
    # a list of rows to insert to that table.
    def table_rows
      # allow specifying fixtures to be ignored by setting `ignore` in `_fixture` section
      fixtures.except!(*ignored_fixtures)

      TableRows.new(
        table_name,
        model_class: model_class,
        fixtures: fixtures,
      ).to_hash
    end

    private
      def model_class=(class_name)
        if class_name.is_a?(Class) # TODO: Should be an AR::Base type class, or any?
          @model_class = class_name
        else
          @model_class = class_name.safe_constantize if class_name
        end
      end

      def ignored_fixtures=(base)
        @ignored_fixtures =
            case base
            when Array
              base
            when String
              [base]
            else
              []
            end

        @ignored_fixtures << "DEFAULTS" unless @ignored_fixtures.include?("DEFAULTS")
        @ignored_fixtures.compact
      end

      # Loads the fixtures from the YAML file at +path+.
      # If the file sets the +model_class+ and current instance value is not set,
      # it uses the file value.

      def read_fixture_files(path)
        yaml_files = Dir["#{path}{.yml,/{**,*}/*.yml}"].select { |f|
          ::File.file?(f)
        }

        raise ArgumentError, "No fixture files found for #{@name}" if yaml_files.empty?

        yaml_files.each_with_object({}) do |file, fixtures|
          FixtureSet::File.open(file) do |fh|
            self.model_class ||= fh.model_class if fh.model_class
            self.model_class ||= default_fixture_model_class
            self.ignored_fixtures ||= fh.ignored_fixtures
            fh.each do |fixture_name, row|
              fixtures[fixture_name] = ActiveRecord::Fixture.new(row, model_class)
            end
          end
        end
      end

      def default_fixture_model_class
        klass = ActiveRecord::FixtureSet.default_fixture_model_name(@name, @config).safe_constantize
        klass if klass && klass < ActiveRecord::Base
      end
  end

  class Fixture # :nodoc:
    include Enumerable

    class FixtureError < StandardError # :nodoc:
    end

    class FormatError < FixtureError # :nodoc:
    end

    attr_reader :model_class, :fixture

    def initialize(fixture, model_class)
      @fixture     = fixture
      @model_class = model_class
    end

    def class_name
      model_class.name if model_class
    end

    def each(&block)
      fixture.each(&block)
    end

    def [](key)
      fixture[key]
    end

    alias :to_hash :fixture

    def find
      raise FixtureClassNotFound, "No class attached to find." unless model_class
      object = model_class.unscoped do
        pk_clauses = fixture.slice(*Array(model_class.primary_key))
        model_class.find_by!(pk_clauses)
      end
      # Fixtures can't be eagerly loaded
      object.instance_variable_set(:@strict_loading, false)
      object
    end
  end
end

ActiveSupport.run_load_hooks :active_record_fixture_set, ActiveRecord::FixtureSet