Apologies, I haven't cleaned this up after my pair a few min ago.

authentication_spec.

require "rails_helper"
require "spec_helper"

describe "API authentication" , :type => :request do

  let!(:user) { Fabricate(:user) }

  context "when faliure" do
    it "has missing or invalid credentials" do
      post "/api/v1/sessions"#, :format => :json
      status = '401'
      error = 'invalid_credentials'
      expect(response.body).to include(status)
      expect(response.body).to include(error)
    end
  end

  context "when success" do
    # it "contains valid credintials" do
    #
    #   post "/api/v1/sessions"#, { email: 'test@example.com', password: '123456', password_confirmation: '123456' }
    #   binding.pry
    # end
    context "the following headers are present" do
      it "Accepts JSON data" do
        post "/api/v1/sessions"#, {email: 'test@example.com', password: '123456'}
        json_header = response.headers
        expect(json_header['Content-Type']).to eq('application/json; charset=utf-8')
      end
      it "has application/x-www-form-urlencoded content-type" do
        post "/api/v1/sessions"
        expect(request.env['CONTENT_TYPE']).to eql("application/x-www-form-urlencoded")
      end
      it "returns status code 200" do
        # request.headers.env['HTTP_USER_EMAIL'], request.headers.env['HTTP_USER_PASSWORD']
        # request.headers.env['HTTP_USER_EMAIL'] = user.email
        # request.headers.env['HTTP_USER_PASSWORD'] = user.password
        headers = {
          env: {
            "HTTP_ENV": {
              "HTTP_USER_EMAIL" => user.email,     # This is what Rails 4 accepts
              "HTTP_USER_PASSWORD" => user.password # This is what Rails 3 accepts
            }
          }
        }
        post "/api/v1/sessions", params: {}, headers: headers
        # binding.pry
        expect(response).to have_http_status(200)
        # expect(response.body).to eq(200)
      end
    end
  end
end