From 7be57950011331b8cdbc0acb21df9395cf171f65 Mon Sep 17 00:00:00 2001
From: Nathan Broadbent <git@ndbroadbent.com>
Date: Tue, 29 Sep 2020 13:54:16 +0800
Subject: [PATCH] Add "scroll-behavior: auto;" CSS to
 Capybara::Server::AnimationDisabler to disable scroll animation

---
 lib/capybara/server/animation_disabler.rb  |  3 +-
 lib/capybara/spec/views/with_animation.erb |  8 ++++++
 spec/shared_selenium_session.rb            | 33 ++++++++++++++++++++++
 3 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/lib/capybara/server/animation_disabler.rb b/lib/capybara/server/animation_disabler.rb
index ed55f23e..86d86596 100644
--- a/lib/capybara/server/animation_disabler.rb
+++ b/lib/capybara/server/animation_disabler.rb
@@ -46,10 +46,11 @@ module Capybara
       DISABLE_MARKUP_TEMPLATE = <<~HTML
         <script defer>(typeof jQuery !== 'undefined') && (jQuery.fx.off = true);</script>
         <style>
-           %<selector>s, %<selector>s::before, %<selector>s::after {
+          %<selector>s, %<selector>s::before, %<selector>s::after {
              transition: none !important;
              animation-duration: 0s !important;
              animation-delay: 0s !important;
+             scroll-behavior: auto !important;
           }
         </style>
       HTML
diff --git a/lib/capybara/spec/views/with_animation.erb b/lib/capybara/spec/views/with_animation.erb
index c64ae040..2c3ef389 100644
--- a/lib/capybara/spec/views/with_animation.erb
+++ b/lib/capybara/spec/views/with_animation.erb
@@ -18,6 +18,14 @@
       });
     </script>
     <style>
+      html {
+        scroll-behavior: smooth;
+      }
+
+      body {
+        min-height: 2000px;
+      }
+
       .transition.away {
           width: 0%;
       }
diff --git a/spec/shared_selenium_session.rb b/spec/shared_selenium_session.rb
index 927e8878..d6dc023d 100644
--- a/spec/shared_selenium_session.rb
+++ b/spec/shared_selenium_session.rb
@@ -388,6 +388,39 @@ RSpec.shared_examples 'Capybara::Session' do |session, mode|
           @animation_session.find_link('animate me away').right_click
           expect(@animation_session).to have_content('Animation Ended', wait: 0.1)
         end
+
+        it 'should scroll the page instantly', requires: [:js] do
+          @animation_session.visit('with_animation')
+          scroll_y = @animation_session.evaluate_script(<<~JS)
+            (function(){
+              window.scrollTo(0,500);
+              return window.scrollY;
+            })()
+          JS
+          expect(scroll_y).to eq 500
+        end
+      end
+
+      context 'when set to `false`' do
+        before(:context) do # rubocop:disable RSpec/BeforeAfterAll
+          skip "Safari doesn't support multiple sessions" if safari?(session)
+          # NOTE: Although Capybara.SpecHelper.reset! sets Capybara.disable_animation to false,
+          # it doesn't affect any of these tests because the settings are applied per-session
+          Capybara.disable_animation = false
+          @animation_session = Capybara::Session.new(session.mode, TestApp.new)
+        end
+
+        it 'should scroll the page with a smooth animation', requires: [:js] do
+          @animation_session.visit('with_animation')
+          scroll_y = @animation_session.evaluate_script(<<~JS)
+            (function(){
+              window.scrollTo(0,500);
+              return window.scrollY;
+            })()
+          JS
+          # measured over 0.5 seconds: 0, 75, 282, 478, 500
+          expect(scroll_y).to be < 500
+        end
       end
 
       context 'if we pass in css that matches elements' do