Add framework for UI testing via bs4

[JasonGrace2282]

This is mostly here so I can explore how I like this solution, and others can see my progress.

The main difference is this now uses BeautifulSoup4, so we can leverage the flexibility of that for more advanced queries. The simple but tedious cases are encapsulated in an Html class, which should be sufficient for most tests.

Testing plan

pytest

Progress

• [X] Implement rough framework
• [x] Add UI tests for assignments app to see if the framework is sufficiently useful.

[JasonGrace2282]

I feel pretty happy with this approach - what do you think @krishnans2006 ?

I did some benchmarking, and I found on my machine (for actual Tin pages):

• Parsing HTML takes on average 0.01s
• Searching through the HTML for a button takes on average 0.002s

And with python -O

• Parsing HTML takes on average 0.006s
• Searching through the HTML for a button takes on average 0.002s

So I'm not too concerned about performance. I've written some light tests to illustrate kind of what I was going for with the UI testing approach, any kind of feedback would be nice :)

[JasonGrace2282]

As discussed internally

• Avoid checking for button and input type=submit unless the tin-btn css class is not found.
• Make button text case insensitive
• Rename visible to visibility or something

[JasonGrace2282]

Looking back at this PR, it might be worth it to use Selenium instead of just parsing html...