Rspec + Capybara : How to click on alert box

I have gone through the post of capybara + click on alert box but nothing seems to be work. Following is my scenario: Scenario: When I click update button An alert box appears which contains "OK" and "Cancel" button. Click on "Ok" then new form appears. I am writing request specs i.e. using rspec and capybara. Main problem is to click on the alert box: Following is my code: ``` context "update" do before(:all) do Capybara.current_driver = :selenium end after(:all) do Capybara.use_default_driver end it "update user to trainer" do click_button('Search') sleep 3 page.evaluate_script('data-confirm = function() { return true; }') page.click('OK') click_button('Upgrade') end end ``` But executing script gives me following error: Failure/Error: page.evaluate_script('data-confirm = function() { return true; }') Selenium::WebDriver::Error::UnexpectedJavascriptError: invalid assignment left-hand side # ./spec/requests/user_upgrades_spec.rb:30 For the second example i.e. page.driver.browser.switch_to.alert.accept My code : ``` context "update" do before(:all) do Capybara.current_driver = :selenium end after(:all) do Capybara.use_default_driver end it "update user to trainer" do click_button('Search') sleep 3 click_button('Upgrade') page.driver.browser.switch_to.alert.accept end end ``` I get error: Failure/Error: page.driver.browser.switch_to.alert.accept Selenium::WebDriver::Error::UnhandledError: Please let me know how to proceed further