Fix tests that fail when running with FAIL_INVALID_TEMPLATE_VARS setting

[michaeljcollinsuk]

Adding FAIL_INVALID_TEMPLATE_VARS = 1 causes a number of tests to fail. It would be worth investigating and fixing these failures

[symroe]

To expand this a little:
FAIL_INVALID_TEMPLATE_VARS is a feature of pytest-django that will check if a template is trying to use a variable from the context that doesn't exit.

It doesn't fail in every case, for example {% if missing_var == "foo" %} won't cause a test fail, as it's valid to check if a variable exists using if, but {{ missing_var }} would fail a test that called that template.

This is really useful to turn on by default in tests, as it's really easy to refactor a Django View without noticing that a particular variable isn't valid in a template anymore. This is especially true when we have lots of cases in the templates - for example checking vars only used in list based elections that we don't generally see.

Done here looks like adding FAIL_INVALID_TEMPLATE_VARS = 1 to pytest.ini and making sure CI passes / fixing all the errors (hard to specify without trying!)

[VirginiaDooley]

One failure within WCIVF is related to the DC base theme: DemocracyClub/dc_base_theme#56

[symroe]

Ah good catch, there is some conversation about this here, that I'd forgotten about until now:

DemocracyClub/UK-Polling-Stations#2899

[michaeljcollinsuk]

In the process of fixing these errors, we've now started to see some strange failures that such as:

E           Failed: Undefined template variable 'SITE_TITLE' in '/Users/michaelcollins/code/dc/WhoCanIVoteFor/wcivf/templates/base.html'

env/lib/python3.6/site-packages/pytest_django/plugin.py:588: Failed

What we can't understand is why this is occurring, as SITE_TITLE is set in the project settings here

And exposed by a context_processor which is correctly set up in the base settings. And we can confirm this is working correctly by checking the source code when running the server/on the live site.

So we're not clear how this test error is still raised - wondering if it could be something about the test setup itself rather than an issue in the codebase?

[michaeljcollinsuk]

Disregard the last comment! Error message was due to syntax errors in the templatetag, which was causing a 500 error to be raised, where SITE_TITLE is unavailable. Have since resolved and will update the PR