Development with Python

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self.browser.find_element_by_tag_name ('button').click()
# The Persona window closes
self.switch_to_new_window('To-Do')
# She can see that she is logged in
self.wait_for_element_with_id ('logout') #
navbar = self.browser.find_element_by_css_selector('.navbar')
self.assertIn( ', navbar.text)
The FT needs a couple of helper functions, both of which do something that’s
very common in Selenium testing: they wait for something to happen. Listings
for them follow.
I found the ID of the Persona login box by opening the site manually, and using
the Firefox debug toolbar (Ctrl+Shift+I). See
Rather than using a “real” email address and having to click through their
authentication screens, we use a “fake” provider. is one; you can also
check out
Evaluate Third-Party Systems’ Test Infrastructure
Testing should be part of how you evaluate third-party systems. When you integrate
with an external service, you’re going to have to think through how you’re going to work
with it in your functional tests.
Often you can just use the same service in your tests and in “real life”. But sometimes
you’re going to want to run against a “test” version of the third-party service. In the case
of this integration with Persona, we could have used a “real” email address; when I first
wrote this chapter, I actually had an FT that clicked through to Yahoo.com, and logged
in with a throwaway account I’d created. The problem is that it made the FT totally
reliant on particular details of Yahoo’s email login screens, which can change at any time.
Instead, MockMyID and PersonaTestUser are both linked to from the Persona docu‐
mentation, and they work very smoothly, letting us test just the important parts of the
integration.
Perhaps more critically, think about payment systems. If you start integrating payments,
they’re going to be one of the most important parts of your site, and you’re going to want
to make sure they’re tested thoroughly … but you don’t want to be putting actual trans‐
actions on real credit cards through, every time you run an FT! So most providers will
provide a “test” version of their payments API. These vary in quality (naming no names),
so make sure you investigate them thoroughly.
252 | Chapter 15: User Authentication, Integrating Third-Party Plugins, and Mocking with JavaScript