How to test a confirm dialog with Cucumber?

The selenium driver now supports this

From Capybara you would access it like this:

page.driver.browser.switch_to.alert.accept

or

page.driver.browser.switch_to.alert.dismiss

or

 page.driver.browser.switch_to.alert.text

Seems like there's no way to do it in Capybara, unfortunately. But if you're running your tests with the Selenium driver (and probably other drivers that support JavaScript), you can hack it. Just before performing the action that would bring up the confirm dialog, override the confirm method to always return true. That way the dialog will never be displayed, and your tests can continue as if the user had pressed the OK button. If you want to simulate the reverse, simply change it to return false.

page.evaluate_script('window.confirm = function() { return true; }')
page.click('Remove')

I've implemented these two web steps in /features/step_definitions/web_steps.rb:

When /^I confirm popup$/ do
  page.driver.browser.switch_to.alert.accept    
end

When /^I dismiss popup$/ do
  page.driver.browser.switch_to.alert.dismiss
end

If you want to specifically test the message being displayed, here's a particularly hacky way to do so. I don't endorse it as beautiful code, but it gets the job done. You'll need to load http://plugins.jquery.com/node/1386/release, or change it to do cookies natively if you don't want jQuery.

Use this sort of story:

Given I am on the menu page for the current booking
And a confirmation box saying "The menu is £3.50 over budget. Click Ok to confirm anyway, or Cancel if you want to make changes." should pop up
And I want to click "Ok"
When I press "Confirm menu"
Then the confirmation box should have been displayed

And these steps

Given /^a confirmation box saying "([^"]*)" should pop up$/ do |message|
  @expected_message = message
end

Given /^I want to click "([^"]*)"$/ do |option|
  retval = (option == "Ok") ? "true" : "false"

  page.evaluate_script("window.confirm = function (msg) {
    $.cookie('confirm_message', msg)
    return #{retval}
  }")
end

Then /^the confirmation box should have been displayed$/ do
  page.evaluate_script("$.cookie('confirm_message')").should_not be_nil
  page.evaluate_script("$.cookie('confirm_message')").should eq(@expected_message)
  page.evaluate_script("$.cookie('confirm_message', null)")
end