Development with Python

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1. Admittedly once you start looking for Python BDD tools, things are a little more confusing.
# She is pleased to see that the error message disappears
error = self.browser.find_element_by_css_selector('.has-error')
self. assertFalse(error.is_displayed()) #
is_displayed() tells you whether an element is visible or not. We can’t just rely
on checking whether the element is present in the DOM, because now we’re
starting to hide elements.
That fails appropriately, but before we move on: three strikes and refactor! We’ve got
several places where we find the error element using CSS. Let’s move it to a helper
function:
functional_tests/test_list_item_validation.py (ch14l002).
def get_error_element(self):
return self.browser.find_element_by_css_selector('.has-error')
I like to keep helper functions in the FT class that’s using them, and
only promote them to the base class when they’re actually needed
elsewhere. It stops the base class from getting too cluttered. YAGNI.
And we then make five replacements in test_list_item_validation, like this one for
example:
functional_tests/test_list_item_validation.py (ch14l003).
# She is pleased to see that the error message disappears
error = self.get_error_element()
self. assertFalse(error.is_displayed())
We have an expected failure:
$ python3 manage.py test functional_tests.test_list_item_validation
[...]
self.assertFalse(error.is_displayed())
AssertionError: True is not false
And we can commit this as the first cut of our FT.
Setting Up a Basic JavaScript Test Runner
Choosing your testing tools in the Python and Django world is fairly straightforward.
The standard library unittest module is perfectly adequate, and the Django test runner
alsomakes a gooddefault choice. There are some alternatives out there is popular,
and I’ve personally found to be very impressive. But there is a clear default option,
and it’s just fine.1
226 | Chapter 13: Dipping Our Toes, Very Tentatively, into JavaScript