Introduces HTTP_REFERER support

https://www.dwightwatson.com/posts/testing-rails-redirect_back-with-rspec

src/api/spec/rails_helper.rb

@@ -85,3 +85,6 @@
 
 # support time helpers
 require 'support/time_helpers'
+
+# support HTTP_REFERER
+require 'support/redirect_back'

src/api/spec/support/redirect_back.rb

@@ -0,0 +1,18 @@
+module RedirectBack
+  # Usage in specs:
+  #
+  #  describe 'POST #create' do
+  #    it 'redirects back' do
+  #      from about_path
+  #      post :create, params: { thing: @thing }
+  #      expect(response).to redirect_to about_url
+  #    end
+  #  end
+  def from(url)
+    request.env['HTTP_REFERER'] = url
+  end
+end
+
+RSpec.configure do |config|
+  config.include RedirectBack
+end