RSpec - 未初始化的常量，例如double

Question

我正在使用TDD方法使用RSpec构建的小型API收到名称错误

NameError:
  uninitialized constant ExpenseTracker::API::Ledger

API.rb

require "sinatra/base"
require "json"

module ExpenseTracker
  class API < Sinatra::Base

def initialize(ledger: Ledger.new) # default value so callers can just say API.new and get the default
  @ledger = ledger
  super() # rest of initialization from Sinatra
end

# Later, callers do this ledger: Ledger.new
app = API.new()

post '/expenses' do
  JSON.generate('expense_id' => 42)
end

get '/expenses/:date' do
  JSON.generate([])
end
end
end

api_spec.rb

require_relative "../../../app/api"
require "rack/test"

module ExpenseTracker

RecordResult = Struct.new(:success?, :expense_id, :error_message)

RSpec.describe API do
include Rack::Test::Methods

def app
  API.new(ledger: ledger)
end

let(:ledger) { instance_double('ExpenseTracker::Ledger') }

describe "POST /expense" do
  context "when the expenseis successfully recorded" do
    it 'returns the expense id'do
      allow(ledger).to receive(:record)
      .with(expense)
      .and_return(RecordResult.new(true, 417, nil))

    post '/expense', JSON.generate(expense)

    parsed = JSON.parse(last_response.body)
    expect(parsed).to include('expense_id': 417)
    end
    it 'responds with a 200 (OK)'
  end

  context "when the expense fails validation" do
    it 'returns an error message'
    it 'responds with 422 (Unprocessable entity)'
  end

end
end
end

以下是我得到的错误：

An error occurred while loading ./api_spec.rb.
Failure/Error:
  def initialize(ledger: Ledger.new) # default value so callers can just say API.new and get the default
    @ledger = ledger
    super() # rest of initialization from Sinatra
  end

NameError:
  uninitialized constant ExpenseTracker::API::Ledger

/Users/Denis/Desktop/TDD/Effective_Testing_with_Rspec3/04-acceptance-specs/expense_tracker/app/api.rb:7:in `initialize'
/Users/Denis/Desktop/TDD/Effective_Testing_with_Rspec3/04-acceptance-specs/expense_tracker/app/api.rb:13:in `<class:API>'
/Users/Denis/Desktop/TDD/Effective_Testing_with_Rspec3/04-acceptance-specs/expense_tracker/app/api.rb:5:in `<module:ExpenseTracker>'
/Users/Denis/Desktop/TDD/Effective_Testing_with_Rspec3/04-acceptance-specs/expense_tracker/app/api.rb:4:in `<top (required)>'
./api_spec.rb:1:in `require_relative'
./api_spec.rb:1:in `<top (required)>'

我错过了什么吗？我试图通过分类帐：Ledger.new到app = API.new，但没有通过这个错误。

任何帮助或想法都会很棒！

Answer 1

好吧，在桌子上敲了很多头后，我想出了这个。

我不得不注释掉app = API.new，因为这还没有实现，每次我都会在规范中加载文件，它会让我误解。

# Later, callers do this ledger: Ledger.new
app = API.new()

现在到下一个失败的规格大声笑！