Add an option for attach_file to allow modifying the elements style since they are so often hidden on the page

lib/capybara/node/actions.rb

@@ -230,6 +230,7 @@ module Capybara
       # @option options [String] id             Match fields that match the id attribute
       # @option options [String] name           Match fields that match the name attribute
       # @option options [String, Array<String>] :class    Match links that match the class(es) provided
+      # @option options [Hash] style   A Hash of CSS styles to change before attempting to attach the file
       #
       # @return [Capybara::Node::Element]  The file field element
       def attach_file(locator, path, options={})
@@ -237,10 +238,31 @@ module Capybara
         Array(path).each do |p|
           raise Capybara::FileNotFound, "cannot attach file, #{p} does not exist" unless File.exist?(p.to_s)
         end
+        # Allow user to update the CSS style of the file input since they are so often hidden on a page
+        if style = options.delete(:style)
+          ff = find(:file_field, locator, options.merge({visible: :all}))
+          _update_style(ff, style)
+        end
         find(:file_field, locator, options).set(path)
       end
 
     private
+      def _update_style(element, style)
+        script = <<-JS
+          var el = arguments[0];
+          var css = arguments[1];
+          for (var prop in css){
+            if (css.hasOwnProperty(prop)) {
+              el.style[prop] = css[prop]
+            }
+          }
+        JS
+        begin
+          session.execute_script(script, element, style)
+        rescue Capybara::NotSupportedByDriverError
+          warn "The :style option is not supported by the current driver - ignoring"
+        end
+      end
 
       def _check_with_label(selector, checked, locator, options)
         locator, options = nil, locator if locator.is_a? Hash

lib/capybara/spec/session/attach_file_spec.rb

@@ -107,4 +107,12 @@ Capybara::SpecHelper.spec "#attach_file" do
       end.to raise_error(Capybara::ElementNotFound)
     end
   end
+
+  context "with :style option", requires: [:js, :es_args] do
+    it "can change the CSS style of the file input field" do
+      @session.visit('/with_js')
+      expect { @session.attach_file("hidden_file", __FILE__) }.to raise_error Capybara::ElementNotFound
+      @session.attach_file("hidden_file", __FILE__, style: { opacity: 1, display: 'block' })
+    end
+  end
 end

lib/capybara/spec/session/evaluate_script_spec.rb

@@ -5,13 +5,13 @@ Capybara::SpecHelper.spec "#evaluate_script", requires: [:js] do
     expect(@session.evaluate_script("1+3")).to eq(4)
   end
 
-  it "should pass arguments to the script" do
+  it "should pass arguments to the script", requires: [:js, :es_args] do
     @session.visit('/with_js')
     @session.evaluate_script("document.getElementById('change').textContent = arguments[0]", "Doodle Funk")
     expect(@session).to have_css('#change', text: 'Doodle Funk')
   end
 
-  it "should support passing elements as arguments to the script" do
+  it "should support passing elements as arguments to the script", requires: [:js, :es_args] do
     @session.visit('/with_js')
     el = @session.find(:css, '#change')
     @session.evaluate_script("arguments[0].textContent = arguments[1]", el, "Doodle Funk")

lib/capybara/spec/session/execute_script_spec.rb

@@ -11,13 +11,13 @@ Capybara::SpecHelper.spec "#execute_script", requires: [:js] do
     expect{ @session.execute_script("$('#change').text('Funky Doodle')") }.not_to raise_error
   end
 
-  it "should pass arguments to the script" do
+  it "should pass arguments to the script", requires: [:js, :es_args] do
     @session.visit('/with_js')
     @session.execute_script("document.getElementById('change').textContent = arguments[0]", "Doodle Funk")
     expect(@session).to have_css('#change', text: 'Doodle Funk')
   end
 
-  it "should support passing elements as arguments to the script" do
+  it "should support passing elements as arguments to the script", requires: [:js, :es_args] do
     @session.visit('/with_js')
     el = @session.find(:css, '#change')
     @session.execute_script("arguments[1].textContent = arguments[0]", "Doodle Funk", el)

lib/capybara/spec/views/with_js.erb

@@ -110,6 +110,11 @@
       <input type="test" name="with-key-events" id="with-key-events">
       <p id="key-events-output"></p>
     </p>
+
+    <p>
+      <input type="file" id="hidden_file" style="opacity:0; display: none;">
+    </p>
+
     <script type="text/javascript">
       // a javascript comment
       var aVar = 123;