From 2ec2a2f295b4477b0b7c298a7f91f456d11aac8d Mon Sep 17 00:00:00 2001
From: Thomas Walpole <twalpole@gmail.com>
Date: Sat, 10 Oct 2020 15:10:56 -0700
Subject: [PATCH] Detect shadow dom elements when calling `path`

---
 lib/capybara/selenium/node.rb          |  3 +++
 lib/capybara/spec/public/test.js       |  7 ++++++-
 lib/capybara/spec/session/node_spec.rb | 11 +++++++++++
 lib/capybara/spec/views/with_js.erb    |  1 +
 spec/dsl_spec.rb                       |  2 +-
 spec/rack_test_spec.rb                 |  1 +
 6 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/lib/capybara/selenium/node.rb b/lib/capybara/selenium/node.rb
index 8f859971..0b7784c2 100644
--- a/lib/capybara/selenium/node.rb
+++ b/lib/capybara/selenium/node.rb
@@ -493,6 +493,9 @@ private
       var xpath = '';
     	var pos, tempitem2;
 
+      if (el.getRootNode && el.getRootNode() instanceof ShadowRoot) {
+        return ": Shadow DOM element - no XPath :"
+        };
       while(el !== xml.documentElement) {
         pos = 0;
         tempitem2 = el;
diff --git a/lib/capybara/spec/public/test.js b/lib/capybara/spec/public/test.js
index 2a2406d2..589b073d 100644
--- a/lib/capybara/spec/public/test.js
+++ b/lib/capybara/spec/public/test.js
@@ -271,5 +271,10 @@ $(function() {
   });
   $('#multiple-file, #hidden_file').change(function(e){
     $('body').append($('<p class="file_change">File input changed</p>'));
-  })
+  });
+
+  var shadow = document.querySelector('#shadow').attachShadow({mode: 'open'});
+  var span = document.createElement('span');
+  span.textContent = 'The things we do in the shadows';
+  shadow.appendChild(span);
 });
diff --git a/lib/capybara/spec/session/node_spec.rb b/lib/capybara/spec/session/node_spec.rb
index 4d43bc71..d0fadae4 100644
--- a/lib/capybara/spec/session/node_spec.rb
+++ b/lib/capybara/spec/session/node_spec.rb
@@ -409,6 +409,17 @@ Capybara::SpecHelper.spec 'node' do
       element = @session.find(:link, 'Second Link')
       expect(@session.find(:xpath, element.path)).to eq(element)
     end
+
+    it 'reports when element in shadow dom', requires: [:shadow_dom] do
+      @session.visit('/with_js')
+      shadow = @session.find(:css, '#shadow')
+      element = @session.evaluate_script(<<~JS, shadow)
+        (function(root){
+          return root.shadowRoot.querySelector('span');
+        })(arguments[0])
+      JS
+      expect(element.path).to eq ": Shadow DOM element - no XPath :"
+    end
   end
 
   describe '#trigger', requires: %i[js trigger] do
diff --git a/lib/capybara/spec/views/with_js.erb b/lib/capybara/spec/views/with_js.erb
index 6c05df99..ea007f88 100644
--- a/lib/capybara/spec/views/with_js.erb
+++ b/lib/capybara/spec/views/with_js.erb
@@ -152,6 +152,7 @@
       <p>This is an HTML5 draggable element.</p>
     </div>
 
+    <div id="shadow"></div>
     <script type="text/javascript">
       // a javascript comment
       var aVar = 123;
diff --git a/spec/dsl_spec.rb b/spec/dsl_spec.rb
index 17751935..de3d140c 100644
--- a/spec/dsl_spec.rb
+++ b/spec/dsl_spec.rb
@@ -8,7 +8,7 @@ class TestClass
 end
 
 Capybara::SpecHelper.run_specs TestClass.new, 'DSL', capybara_skip: %i[
-  js modals screenshot frames windows send_keys server hover about_scheme psc download css driver scroll spatial html_validation
+  js modals screenshot frames windows send_keys server hover about_scheme psc download css driver scroll spatial html_validation shadow_dom
 ] do |example|
   case example.metadata[:full_description]
   when /has_css\? should support case insensitive :class and :id options/
diff --git a/spec/rack_test_spec.rb b/spec/rack_test_spec.rb
index 1aae9601..0e0b1334 100644
--- a/spec/rack_test_spec.rb
+++ b/spec/rack_test_spec.rb
@@ -27,6 +27,7 @@ skipped_tests = %i[
   scroll
   spatial
   html_validation
+  shadow_dom
 ]
 Capybara::SpecHelper.run_specs TestSessions::RackTest, 'RackTest', capybara_skip: skipped_tests do |example|
   case example.metadata[:full_description]