Add authentication shared context

spec/shared/contexts.rb

+require 'rails_helper'
+require 'rspec_api_documentation'
+require 'rspec_api_documentation/dsl'
+require 'spec_helper'
+
+RSpec.shared_context "authentication", shared_context: :metadata do
+  let(:auth_client) { @auth_headers['client'] }
+  let(:uid) { @auth_headers['uid'] }
+  let(:access_token) { @auth_headers['access-token'] }
+
+  def authenticate(user)
+    @auth_headers = user.create_new_auth_token
+  end
+end