Add spec for absolute URLs.

lib/rack/test.rb

@@ -197,6 +197,7 @@ def follow_redirect!
 
         # Compute the next location by appending the location header with the
         # last request, as per https://tools.ietf.org/html/rfc7231#section-7.1.2
+        # Adding two absolute locations returns the right-hand location
         next_location = URI.parse(last_request.url) + URI.parse(last_response['Location'])
 
         send(

spec/fixtures/fake_app.rb

@@ -28,6 +28,10 @@ class FakeApp < Sinatra::Base
         'Hello World!'
       end
 
+      get '/absolute/redirect' do
+        [301, { 'location' => 'https://www.google.com' }, []]
+      end
+
       post '/redirect' do
         if params['status']
           redirect to('/redirected'), Integer(params['status'])

spec/rack/test_spec.rb

@@ -366,6 +366,11 @@ def close
       expect(last_request.env['HTTP_REFERER']).to eql('http://example.org/redirect')
     end
 
+    it 'follows absolute redirects' do
+      get '/absolute/redirect'
+      expect(last_response.headers['location']).to be == 'https://www.google.com'
+    end
+
     it 'follows nested redirects' do
       get '/nested/redirect'