為什么ruby rails to_json返回字符串而不是哈希？

Question

我正在學習使用ruby版本2.3.1和rails版本5.0.7構建JSON api的教程。 該教程位於https://scotch.io/tutorials/build-a-restful-json-api-with-rails-5-part-two運行RSpec測試時，我得到：

失敗：

1）當請求有效時，AuthenticationController POST / auth / login返回認證令牌失敗/錯誤：在{post'auth / login'之前，參數：valid_credentials，標頭：標頭}

 NoMethodError:
   undefined method `symbolize_keys' for "{\"email\":\"foo@bar.com\",\"password\":\"foobar\"}":String
 # ./spec/controllers/authentication_controller_spec.rb:32:in `block (4 levels) in <top (required)>'
 # ./spec/rails_helper.rb:85:in `block (3 levels) in <top (required)>'
 # ./spec/rails_helper.rb:84:in `block (2 levels) in <top (required)>'

2）AuthenticationController POST / auth / login請求無效時返回失敗消息錯誤/錯誤：{post'/ auth / login'之前，參數：invalid_credentials，標頭：headers}

 NoMethodError:
   undefined method `symbolize_keys' for #<String:0x007fcb133e88f8>
 # ./spec/controllers/authentication_controller_spec.rb:41:in `block (4 levels) in <top (required)>'
 # ./spec/rails_helper.rb:85:in `block (3 levels) in <top (required)>'
 # ./spec/rails_helper.rb:84:in `block (2 levels) in <top (required)>'

它所引用的AuthenticationControllerSpec如下：

    require 'rails_helper'
    RSpec.describe AuthenticationController, type: :controller do
      # Authentication test suite
      describe 'POST /auth/login' do
        # create test user
        let!(:user) { create(:user) }

        # set headers for authorization
        let(:headers) { valid_headers.except('Authorization')  }

        # set test valid and invalid credentials
        let(:valid_credentials) do
           { 
              email: user.email, 
              password: user.password 
           }.to_json 
        end # let(:valid_credentials) do 

        let(:invalid_credentials) do 
          {
             email: Faker::Internet.email,
             password: Faker::Internet.password
          }.to_json
        end # let(:invalid_credentials) do 

        # set request.headers to our custom headers
        # before { allow(request).to receive(:headers).and_return(headers) }

        # returns auth token when request is valid
        context 'when request is valid' do
          before { post 'auth/login', params: valid_credentials, headers: headers }

          it 'returns an authentication token' do
            expect(json['auth_token']).not_to be_nil
          end #  it 'returns an authentication token' do
end #     context 'when request is valid' do

        # returns failure message when request is invalid
        context 'When request is invalid' do
          before { post '/auth/login', params: invalid_credentials, headers: headers }

          it 'returns a failure message' do
            expect(json['message']).to match(/Invalid credentials/)
          end # it 'returns a failure message' do
        end # context 'When request is invalid' do


      end # describe 'POST /auth/login' do

    end # RSpec.describe AuthenticationController, type: :controller do

我認為唯一其他相關文件是此模塊：

    module RequestSpecHelper
      # Parse JSON response to ruby hash
      def json
        JSON.parse(response.body)
      end
    end

感謝您的協助。

Answer 1

不要手動將參數轉換為JSON。 RSpec會自動為您執行此操作，並期望參數的哈希而不是字符串。

let(:valid_credentials) do
  { 
    email: user.email, 
    password: user.password 
  }
end

let(:invalid_credentials) do 
  {
    email: Faker::Internet.email,
    password: Faker::Internet.password
  }
end

另外，對於一個新項目，我將跳過控制器測試， 直接尋求更規范的請求規范 。