現象

config.eager_load = false の環境で1ファイル内に複数classを定義した際、ファイル名と異なるclassのautoloadが機能しない

環境

Ruby: 2.3.1
Rails: 4.2.7.1

1ファイル内に複数のclass

source

# app/models/samples/foo.rb

class Samples::SampleError < StandardError; end

module Samples
  class Foo
  end
end

rails console

config.eager_load = false

> defined? Samples::SampleError
# => nil

> Samples::SampleError
# => NameError: uninitialized constant Samples::SampleError

config.eager_load = true

> defined? Samples::SampleError
# => "constant"

> Samples::SampleError
# => Samples::SampleError

1ファイル1class

source

# app/models/samples/sample_error.rb

class Samples::SampleError < StandardError; end

# app/models/samples/foo.rb

module Samples
  class Foo
  end
end

rails console

config.eager_load = false

> defined? Samples::SampleError
# => nil

> Samples::SampleError
# => Samples::SampleError

config.eager_load = true

> defined? Samples::SampleError
# => "constant"

> Samples::SampleError
# => Samples::SampleError

何が困るか

例えば下記のように、抽象クラスから Samples::Foo を呼び出すような実装をした際

# app/models/samples/abstract.rb

module Samples
  class Abstract
    def self.exec
      Foo.new.exec
    end
  end
end

# app/models/samples/foo.rb

class Samples::SampleError < StandardError; end

module Samples
  class Foo
    def exec
      raise SampleError
    end
  end
end

# spec/models/samples/abstract_spec.rb

require 'rails_helper'

describe Samples::Abstract, type: :model do
  describe ".exec" do
    it "Samples::SampleErrorが発生する" do
      expect { Sample::Abstract.exec }.to raise_error Samples::SampleError
    end
  end
end

単一ファイルのテストを実行した際、 uninitialized constant Samples::SampleError が発生する

$ rspec spec/models/samples/abstract_spec.rb

# Randomized with seed 965
# 
# Samples::Abstract
#   .exec
#     Samples::SampleErrorが発生する (FAILED - 1)
# 
# Failures:
# 
#   1) Samples::Abstract.exec Samples::SampleErrorが発生する
#      Failure/Error: expect { Sample::Abstract.exec }.to raise_error Samples::SampleError
# 
#      NameError:
#        uninitialized constant Samples::SampleError
#      # ./spec/models/samples/abstract_spec.rb:6:in `block (3 levels) in <top (required)>'
# 
# Finished in 0.01472 seconds (files took 3.95 seconds to load)
# 1 example, 1 failure
# 
# Failed examples:
# 
# rspec ./spec/models/samples/abstract_spec.rb:5 # Samples::Abstract.exec Samples::SampleErrorが発生する
# 
# Randomized with seed 965