是否可以在调用期间将参数传递给 let 阻塞？

Question

我已经开始使用 Rspec 并且现在我编写了几个成功且非常困难的测试。但由于我需要更多练习，所以我对这些测试做了几次重构。

我在 Rspec 的文档中没有找到我的问题的答案，这就是我在这里的原因。

问题是关于指令let，它提供了通过第一次调用返回一些对象的能力，而不仅仅是，你知道的。

我当前的 rspec 代码部分是：

RSpec.describe 'Users', type: :request do
  describe 'profiles' do
    context 'should be visible by' do
      it 'related company managers' do
        company = create(:company)
        sign_in create(:manager, :company, company: company) # Pay attention on this
        get user_path(create(:member, :company, company: company)) # this
        expect(response).to have_http_status 200
      end

      it 'related company owners' do
        company = create(:company)
        sign_in create(:owner, :company, company: company) # this
        get user_path(create(:member, :company, company: company)) # and this
        expect(response).to have_http_status 200
      end
    end
  end
end

在用户规范下只有两个 63 示例，但它们已经足够了。我想重构代码以使用let，它将定义一个带参数的方法，如下所示：

RSpec.describe 'Users', type: :request do
  let(:member) do |entity_name = :company, entity = create(entity_name)|
    create :member, entity_name, entity_name => entity
  end
  let(:manager) do |entity_name = :company, entity = create(entity_name)|
    create :manager, entity_name, entity_name => entity
  end
  let(:owner) do |entity_name = :company, entity = create(entity_name)|
    create :owner, entity_name, entity_name => entity
  end

  describe 'profiles' do
    context 'should be visible by' do
      it 'related company managers' do
        company = create(:company)
        sign_in manager(:company, company) # Become more readable here
        get user_path(member(:company, company)) # here
        expect(response).to have_http_status 200
      end

      it 'related company owners' do
        company = create(:company)
        sign_in owner(:company, company) # here
        get user_path(member(:company, company)) # and here.
        expect(response).to have_http_status 200
      end
    end
  end
end

在重构之后，Guard 说：

  1) Users profiles should be visible by related company managers
     Failure/Error: sign_in manager(:company, company) # Become more readable here

     ArgumentError:
       wrong number of arguments (given 2, expected 0)
     # ./spec/requests/users_spec.rb:38:in `block (4 levels) in <top (required)>'

从我看到的Rspec核心的memorized_helpers.rb：

def let(name, &block)
  # We have to pass the block directly to `define_method` to
  # allow it to use method constructs like `super` and `return`.
  raise "#let or #subject called without a block" if block.nil?
  raise(
    "#let or #subject called with a reserved name #initialize"
  ) if :initialize == name
  MemoizedHelpers.module_for(self).__send__(:define_method, name, &block)

  # Apply the memoization. The method has been defined in an ancestor
  # module so we can use `super` here to get the value.
  if block.arity == 1
    define_method(name) { __memoized.fetch_or_store(name) { super(RSpec.current_example, &nil) } }
  else
    define_method(name) { __memoized.fetch_or_store(name) { super(&nil) } }
  end
end

看起来let 的块应该用参数定义。或不？ 我没有足够的经验来确定它，我很乐意找到它。

Answer 1

我找到了可能的解决方案：返回一个 lambda 并就地调用它

RSpec.describe 'Users', type: :request do
  let(:member) do
    ->(entity_name = :company, entity = create(entity_name)) do
      create :member, entity_name, entity_name => entity
    end
  end
  let(:manager) do
    ->(entity_name = :company, entity = create(entity_name)) do
      create :manager, entity_name, entity_name => entity
    end
  end
  let(:owner) do
    ->(entity_name = :company, entity = create(entity_name)) do
      create :owner, entity_name, entity_name => entity
    end
  end

  describe 'profiles' do
    context 'should be visible by' do
      it 'related company managers' do
        company = create(:company)
        sign_in manager.(:company, company) # Pay attention on the dot here
        get user_path(member.(:company, company)) # here
        expect(response).to have_http_status 200
      end

      it 'related company owners' do
        company = create(:company)
        sign_in owner.(:company, company) # here
        get user_path(member.(:company, company)) # and here.
        expect(response).to have_http_status 200
      end
    end
  end
end

这不是我想要的，但看起来像。

Answer 2

我想你想要这样的东西：

RSpec.describe 'Users', type: :request do
  describe 'profiles' do
    let(:request) { get user_path(user) }
    let(:user)    { create(:member, :company, company: company) }
    let(:company) { create(:company) }

    shared_examples_for 'has visibility to user' do
      before { sign_in employee }

      it do 
        request
        expect(response).to have_http_status(:success)
      end
    end

    context 'manager' do
      let(:employee) { create(:manager, company: company) }

      it_behaves_like 'has visibility to user'
    end

    context 'owner' do
      let(:employee) { create(:owner, company: company) }

      it_behaves_like 'has visibility to user'
    end
  end
end

同样，您应该能够执行以下操作：

it_behaves_like 'has visibility to user' do
 let(:employee) { create(:manager, company: company) }
end

shared examples。我建议查看http://www.betterspecs.org/。

（除此之外，将工厂命名为 :member 而不是 :user 令人困惑，因为 GET 请求是针对 user_path 的；我建议重命名它。）

Answer 3

另一个解决方案是创建助手。比如在spec/support/users_helper.rb中创建一个文件。

module UsersSpecHelper

  def member(entity = :company)
    create :member, *entity(entity)
  end

  def manager(entity = :company)
    create :manager, *entity(entity)
  end

  def owner(entity = :company)
    create :owner, *entity(entity)
  end

  private

    def entity(entity)
      if entity.is_a? Symbol
        [entity, entity => create(entity)]
      else
        name = entity.class.to_s.downcase.to_sym
        [name, name => entity]
      end
    end
end

RSpec.configure do |config|
  config.include UsersSpecHelper, type: :request
end

在spec/rails_helper.rb 行中取消注释：

Dir[Rails.root.join('spec/support/**/*.rb')].each { |f| require f }

然后它可以更好地使用：

RSpec.describe 'Users', type: :request do
  describe 'profiles' do
    context 'should be visible by' do
      it 'managers of related company' do
        company = create(:company)
        sign_in manager(company) # Changes are here
        get user_path(member(company)) # here
        expect(response).to have_http_status 200
      end

      it 'owners of related company' do
        company = create(:company)
        sign_in owner(company) # here
        get user_path(member(company)) # and here.
        expect(response).to have_http_status 200
      end
    end
  end
end