[fix] selenium set_text passing in empty string with options

If an empty value if passed in with a clear option, it seems that the
caller's intent is for the option to be honored regardless of the value
to be set in the field.

Just passing in a blank value would behave as it did before.

Updated spec to also attach an input event listener to
`with_change_event`

lib/capybara/selenium/node.rb

@@ -209,7 +209,7 @@ private
   def set_text(value, options)
     if readonly?
       warn "Attempt to set readonly element with value: #{value} \n *This will raise an exception in a future version of Capybara"
-    elsif value.to_s.empty?
+    elsif value.to_s.empty? && options[:clear].nil?
       native.clear
     else
       if options[:clear] == :backspace

lib/capybara/spec/public/test.js

@@ -37,6 +37,9 @@ $(function() {
   $('#with_change_event').change(function() {
     $('body').append($('<p class="change_event_triggered"></p>').text(this.value));
   });
+  $('#with_change_event').on('input', function() {
+    $('body').append($('<p class="input_event_triggered"></p>').text(this.value));
+  });
   $('#checkbox_with_event').click(function() {
     $('body').append('<p id="checkbox_event_triggered">Checkbox event triggered</p>');
   });

spec/shared_selenium_session.rb

@@ -71,6 +71,16 @@ RSpec.shared_examples "Capybara::Session" do |session, mode|
       end
     end
 
+    context '#fill_in_with empty string and no options' do
+      it 'should trigger change when clearing a field' do
+        @session.visit('/with_js')
+        @session.fill_in('with_change_event', with: '')
+        # click outside the field to trigger the change event
+        @session.find(:css, 'body').click
+        expect(@session).to have_selector(:css, '.change_event_triggered', match: :one)
+      end
+    end
+
     context "#fill_in with { :clear => :backspace } fill_option", requires: [:js] do
       it 'should fill in a field, replacing an existing value' do
         @session.visit('/form')
@@ -96,6 +106,15 @@ RSpec.shared_examples "Capybara::Session" do |session, mode|
         @session.find(:css, 'body').click
         expect(@session).to have_selector(:css, '.change_event_triggered', match: :one)
       end
+
+      it 'should trigger input event field_value.length times' do
+        @session.visit('/with_js')
+        @session.fill_in('with_change_event', with: '',
+                         fill_options: { :clear => :backspace })
+        # click outside the field to trigger the change event
+        @session.find(:css, 'body').click
+        expect(@session).to have_xpath('//p[@class="input_event_triggered"]', count: 13)
+      end
     end
 
     context "#fill_in with { clear: :none } fill_options" do