Regression? Class variable access in a helper function.

[dblock]

  context 'with static variable access' do
    before do
      @@static_variable = 42

      subject.helpers do
        def get_static_variable
          @@static_variable
        end
      end

      subject.get do
        get_static_variable
      end
    end
    it 'preserves self' do
      get '/'
      expect(last_response.status).to eq 200
      expect(last_response.body).to eq '42'
    end
  end

  1) Grape::API with static variable access preserves self
     Failure/Error: @@static_variable
     NameError:
       uninitialized class variable @@static_variable in #<Module:0x007fb4646c72b0>
     # ./spec/grape/api_spec.rb:2720:in `get_static_variable'
     # ./spec/grape/api_spec.rb:2725:in `block (4 levels) in <top (required)>'
     # ./lib/grape/endpoint.rb:47:in `call'

At least needs to be documented in UPGRADING.

[dblock]

Documented this in UPGRADING in b8b0ef1. Will leave this by design.