Posted over 7 years ago. Visible to the public. Repeats.

Waiting for page loads and AJAX requests to finish with Capybara

If you're using the Capybara webdriver, steps sometimes fail because the browser hasn't finished loading the next page yet, or it still has a pending AJAX request. You'll often see workarounds like

When I wait for the page to load Then ...

Workarounds like this do not work reliably, will result in flickering tests and should be avoided. There is no known reliable way to detect if the browser has finished loading the page.


Instead you should wait until you can observe the result of a page load. E.g. if you make an AJAX requests to populate autocomplete suggestions, wait until you can see the suggestions box:

wait_until do page.has_css?('.suggestions') end

You don't need to do this if you're using Spreewald's web steps, because the steps take care of this automatically. They do this by wrapping all assertions into a helper called patiently do, like this:

Then /^I should see "([^\"]*)" in the HTML$/ do |text| patiently do body = page.body expect(body).to have_content(text) end end

This works by rerunning the inner block several times till it succeeds or a timeout is reached, when we're inside a @javascript feature.

You're encouraged to use this for all of your own steps that check for page content. If a step does not actually access the page object, they do not need this, of course.

Grouping retriable statements

Note that you must wrap patiently around groups of statements that need to be retried together. For instance, the following might not work:

Then /^I should see "([^\"]*)" in the HTML$/ do |text| body = page.body patiently do expect(body).to have_content(text) end end

In this case we might have fetched body from the page, then body is removed from the DOM. The patiently call will then always fail since we never re-fetch a fresh body.

By refactoring problematic code and creating automated tests, makandra can vastly improve the maintainability of your Rails application.

Owner of this card:

Tobias Kraze
Last edit:
6 months ago
by Johanna Hartmann
About this deck:
We are makandra and do test-driven, agile Ruby on Rails software development.
License for source code
Posted by Tobias Kraze to makandra dev
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