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Let’s do a commit at this point, because we’ve got at least a placeholder for our FT, we’ve
got a useful modification of the
create_pre_authenticated_session
function, and
we’re about to embark on a bit of an FT refactor:
$
git add functional_tests
$
git commit -m "New FT for sharing, move session creation stuff to base"
Implementing the Selenium Interact/Wait Pattern
Before we continue, let’s take a closer look at the interactions with the site which we
have in our FT so far:
functional_tests/test_sharing.py.
# Edith goes to the home page and starts a list
self
.
browser
=
edith_browser
self
.
browser
.
get
(
self
.
server_url
)
self
.
get_item_input_box
()
.
send_keys
(
'Get help
\n
'
)
#
# She notices a "Share this list" option
share_box
=
self
.
browser
.
find_element_by_css_selector
(
'input[name=email]'
)
#
self
.
assertEqual
(
share_box
.
get_attribute
(
'placeholder'
),
'your-friend@example.com'
)
Interaction with site
Assumption about updated state of page
We learned in the last chapter that it’s dangerous to assume too much about the state of
the browser after we do an interaction (like
send_keys
). In theory,
implicitly_wait
will make sure that, if the call to
find_element_by_css_selector
doesn’t find our
input[name=email]
at first, it will silently retry a few times. But it can also go wrong—
imagine if there was an input on the previous page, with the same
name=email
, but a
different placeholder text? We’d get a strange failure, because Selenium could theoreti‐
cally pick up the element from the previous page while the new page is loading. That
tends to raise a
StaleElementException
.
Unexpected
StaleElementException
errors from Selenium often
mean you have some kind of race condition. You should probably
specify an explicit interaction/wait pattern.
Instead, it’s always prudent to follow the “wait-for” pattern whenever we want to check
on the effects of an interaction that we’ve just triggered. Something like this:
functional_tests/test_sharing.py.
self
.
get_item_input_box
()
.
send_keys
(
'Get help
\n
'
)
Implementing the Selenium Interact/Wait Pattern
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