Rspec testing API versioning

Question

I'm working with a web api in rails 4.1.8 and i'm doing some testing but always is returning me

Failure/Error: post '/v1/users', subdomain: 'api', user: @user.to_json, format: :json
 ActionController::UrlGenerationError:
   No route matches {:action=>"/v1/users", :controller=>"api/v1/users", :format=>:json, :subdomain=>"api", :user=>"JSON_OBJ"}

but if i test it in the browser with Advance Rest Console it works, i don't know what i'm doing wrong

here is me code

routes.rb

namespace :api, path: '/', constraints: {subdomain: 'api'}, defaults: { format: :json } do
  namespace :v1 do
    with_options except: [:edit, :new] do |except|
      except.resources :users do
        collection do
          post 'login'
          post 'showme'
        end
      end
      except.resources :products
      except.resources :locations
    end
  end
end

and my controller spec

module API
  module V1
    describe UsersController do
     before do
        request.host = "api.example.com"
        expect({:post => "http://#{request.host}/v1/users"}).to(
          route_to( controller: "api/v1/users",
                    action: "create",
                    subdomain: 'api',
                    format: :json
                  )
        ) # => PASS

        # token expectations
        @auth_token = allow(JWT::AuthToken).to(
          receive(:make_token).and_return("mysecretkey")
        )
        expect(JWT::AuthToken.make_token({}, 3600)).to eq("mysecretkey")
      end
      describe "Create User" do
        before(:each) do
          @user = FactoryGirl.attributes_for :user
        end

        it 'should return a token' do
          post '/v1/users', subdomain: 'api', user: @user.to_json, format: :json # Error
          response_body = JSON.parse(response.body, symbolize_names: true)
          expect(response_body['token']).to eql "mysecretkey"
        end
      end
    end
  end
end

rake routes

   login_api_v1_users POST   /v1/users/login(.:format)   api/v1/users#login {:format=>:json, :subdomain=>"api"}

   showme_api_v1_users POST   /v1/users/showme(.:format)  api/v1/users#showme {:format=>:json, :subdomain=>"api"}

   api_v1_users GET    /v1/users(.:format)         api/v1/users#index {:format=>:json, :subdomain=>"api"}

                POST   /v1/users(.:format)         api/v1/users#create {:format=>:json, :subdomain=>"api"}

    api_v1_user GET    /v1/users/:id(.:format)     api/v1/users#show {:format=>:json, :subdomain=>"api"}

                PATCH  /v1/users/:id(.:format)     api/v1/users#update {:format=>:json, :subdomain=>"api"}

                PUT    /v1/users/:id(.:format)     api/v1/users#update {:format=>:json, :subdomain=>"api"}

                DELETE /v1/users/:id(.:format)     api/v1/users#destroy {:format=>:json, :subdomain=>"api"}

Answer 1

As described in http://api.rubyonrails.org/classes/ActionController/TestCase/Behavior.html which is referenced in https://www.relishapp.com/rspec/rspec-rails/docs/controller-specs, the first argument to post in your RSpec example is the name of the controller method to be called (i.e. :create in your case), not the route to that method.