Add validation_message filter to field and fillable_field selectors

lib/capybara/selector.rb

@@ -40,6 +40,7 @@ require 'capybara/selector/definition'
 #       * :disabled (Boolean, :all) - Match disabled field? (Default: false)
 #       * :multiple (Boolean) - Match fields that accept multiple values
 #       * :valid (Boolean) - Match fields that are valid/invalid according to HTML5 form validation
+#       * :validation_message (String, Regexp) - Matches the elements current validationMessage
 #
 # * **:fieldset** - Select fieldset elements
 #   * Locator: Matches id, {Capybara.configure test_id}, or contents of wrapped legend
@@ -79,6 +80,7 @@ require 'capybara/selector/definition'
 #       * :disabled (Boolean, :all) - Match disabled field? (Default: false)
 #       * :multiple (Boolean) - Match fields that accept multiple values
 #       * :valid (Boolean) - Match fields that are valid/invalid according to HTML5 form validation
+#       * :validation_message (String, Regexp) - Matches the elements current validationMessage
 #
 # * **:radio_button** - Find radio buttons
 #   * Locator: Match id, {Capybara.configure test_id} attribute, name, or associated label text
@@ -178,6 +180,12 @@ Capybara::Selector::FilterSet.add(:_field) do
   node_filter(:valid, :boolean) { |node, value| node.evaluate_script('this.validity.valid') == value }
   node_filter(:name) { |node, value| !value.is_a?(Regexp) || value.match?(node[:name]) }
   node_filter(:placeholder) { |node, value| !value.is_a?(Regexp) || value.match?(node[:placeholder]) }
+  node_filter(:validation_message) do |node, msg|
+    vm = node[:validationMessage]
+    (msg.is_a?(Regexp) ? msg.match?(vm) : vm == msg.to_s).tap do |res|
+      add_error("Expected validation message to be #{msg.inspect} but was #{vm}") unless res
+    end
+  end
 
   expression_filter(:name) do |xpath, val|
     builder(xpath).add_attribute_conditions(name: val)
@@ -198,7 +206,7 @@ Capybara::Selector::FilterSet.add(:_field) do
     desc
   end
 
-  describe(:node_filters) do |checked: nil, unchecked: nil, disabled: nil, valid: nil, **|
+  describe(:node_filters) do |checked: nil, unchecked: nil, disabled: nil, valid: nil, validation_message: nil, **|
     desc, states = +'', []
     states << 'checked' if checked || (unchecked == false)
     states << 'not checked' if unchecked || (checked == false)
@@ -206,6 +214,7 @@ Capybara::Selector::FilterSet.add(:_field) do
     desc << " that is #{states.join(' and ')}" unless states.empty?
     desc << ' that is valid' if valid == true
     desc << ' that is invalid' if valid == false
+    desc << " with validation message #{validation_message.to_s.inspect}" if validation_message
     desc
   end
 end

lib/capybara/selector/definition/fillable_field.rb

@@ -18,7 +18,7 @@ Capybara.add_selector(:fillable_field, locator_type: [String, Symbol]) do
     end
   end
 
-  filter_set(:_field, %i[disabled multiple name placeholder valid])
+  filter_set(:_field, %i[disabled multiple name placeholder valid validation_message])
 
   node_filter(:with) do |node, with|
     val = node.value

lib/capybara/spec/session/has_field_spec.rb

@@ -60,6 +60,22 @@ Capybara::SpecHelper.spec '#has_field' do
     end
   end
 
+  context 'with validation message', requires: [:html_validation] do
+    it 'should accept a regexp' do
+      @session.fill_in('form_zipcode', with: '1234')
+      expect(@session).to have_field('form_zipcode', validation_message: /match the requested format/)
+      expect(@session).not_to have_field('form_zipcode', validation_message: /random/)
+    end
+
+    it 'should accept a string' do
+      @session.fill_in('form_zipcode', with: '1234')
+      expect(@session).to have_field('form_zipcode', validation_message: 'Please match the requested format.')
+      expect(@session).not_to have_field('form_zipcode', validation_message: 'match the requested format.')
+      @session.fill_in('form_zipcode', with: '12345')
+      expect(@session).to have_field('form_zipcode', validation_message: '')
+    end
+  end
+
   context 'with type' do
     it 'should be true if a field with the given type is on the page' do
       expect(@session).to have_field('First Name', type: 'text')

lib/capybara/spec/views/form.erb

@@ -140,7 +140,7 @@
 
   <p>
     <label for="form_zipcode">Zipcode</label>
-    <input type="text" maxlength="5" name="form[zipcode]" id="form_zipcode" />
+    <input type="text" maxlength="5" name="form[zipcode]" id="form_zipcode" pattern="[0-9]{5,9}" />
   </p>
 
   <p>

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
+  js modals screenshot frames windows send_keys server hover about_scheme psc download css driver scroll spatial html_validation
 ] do |example|
   case example.metadata[:full_description]
   when /has_css\? should support case insensitive :class and :id options/

spec/rack_test_spec.rb

@@ -26,6 +26,7 @@ skipped_tests = %i[
   css
   scroll
   spatial
+  html_validation
 ]
 Capybara::SpecHelper.run_specs TestSessions::RackTest, 'RackTest', capybara_skip: skipped_tests do |example|
   case example.metadata[:full_description]