Fixes #46 - Add Flask blueprint handler for GitHub webhooks + helper methods

[miketaylr]

Tests are failing for this (tiny) linting error:

./ochazuke/webhooks/helpers.py:201:1: W293 blank line contains whitespace
Exited with code 1

[miketaylr]

Looks really good! I'll let @karlcow have a peek too.

[laghee]

@karlcow Thanks for the resources. And this:

It's often easier to have data-in -> (massaging) -> data-out. Then write.

...makes tons of sense.

I'm going to try extracting the database actions into discrete db-utility functions (assuming that doesn't cause issues with session/context -- probably flask_sqlalchemy can handle it):

• either one per table: issue, event, label, milestone operations or
• one per operation type: add_thing(), remove_thing(), update_thing()

(or magic-idea-that-occurs-while-tinkering)

[laghee]

UPDATE: Experimenting with the same webhooks set up on my old local webcompat test-repo, it turns out that GH does some weird stuff with issue events. When milestones/labels are added while opening an issue, they still send out separate webhooks for those "additional" events.

Example: - I opened an issue with a milestone and two labels. - Not only did the milestone/labels come through in the original opened action, - That also triggered one milestoned action and two labeled actions (which... fine, I guess?) - But then the truly bizarre thing is that each of the two separate labeled webhook payloads contains both labels. 🤔 😕

So... odd and dumb that we could potentially perform busywork data updates that aren't actually changing anything. But probably won't break too much.

This means I need to add some logic for processing multiple labels, though. I had assumed there would only ever be one label per payload. (ahhh, assumptions... <insert mildly offensive cliche here>)

EDIT: Errrrhm, never mind! Turns out I mixed up the labels key in the payload with the label key. (Note to self: Never try to parse anything too intricate on a Friday afternoon. 🤦‍♀️ )

[laghee]

@miketaylr @karlcow I made changes based on discussion and requests:

• changed all non-essential dict.get usages to dict['key']
• changed all issue header usages to title to match github (also updated in models.py PR #52)
• refactored the database ops into a single, separate helper (make_change_to_database)
• pulled issue-event routing functionality (update_db) back into the webhook handler to make testing easier (hopefully)

Going back to hacking on tests with my new resources...