Refactor: centralize management of Django routes

[thekaveman]

Closes #2303

Part of #2252

Context setting

Right now we have Django route strings, e.g. app_name:view_name all over the place: in views, in middleware, in models, in templates, in URL config, in tests... it is truly a mess and difficult to get a handle on.

This PR refactors every route string in the app into a top-level benefits/routes.py module. Everywhere else mentioned above that needs a route string, uses this central module to get it.

Implementation details

• Create a class benefits.routes.Routes with an @property for every route in the app
• Property names are exactly like the current ROUTE_NAME variables, cleaned up and organized by app e.g.
  • INDEX for the homepage
  • HELP for the help page
  • ELIGIBILITY_INDEX for the entry to eligibility phase
  • ENROLLMENT_INDEX for the entry to enrollment phase
  • etc.
• Note: I decided against CORE_ routes, it felt a little extra... but happy to add that for consistency.
• Property docstrings """Doc strings""" are used to describe what the route is for, handy for devs using these props
• Define an instance of the class in the module: routes = Routes()
• This instance is imported and used elsewhere e.g. in views:

  from benefits.routes import routes
  
  redirect(reverse(routes.INDEX))

• Helper function on the class Routes.name(route: str) -> str gets the name portion, e.g. name from app:name
• urls.py uses this Routes.name() helper when registering URLs, avoiding duplication
• New benefits.core.context_processors.routes() puts every route in the template context, so all hardcoded routes could be removed from templates:

  <a href="{% url routes.INDEX %}">Go home</a>

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
benefits
routes.py
benefits/core
context_processors.py
middleware.py
models.py
session.py
urls.py
views.py
benefits/eligibility
forms.py
urls.py
views.py					32
benefits/enrollment
forms.py
urls.py
views.py					246
benefits/in_person
urls.py
views.py
benefits/oauth
middleware.py
redirects.py
urls.py
views.py
Project Total

This report was generated by python-coverage-comment-action

[lalver1]

The code looks good to me and I didn't see any dangling routes (searched for the regex "[A-Za-z0-9_]*:[A-Za-z0-9_]*" and the results are all in routes.py). I only saw one place where the route changed but I think the change makes sense 👍

[lalver1]

I think this is correct, since if the session has an agency, the origin is agency.index_url --> routes.AGENCY_INDEX --> "core:agency_index" (url "/cst"). But originally origin was set to "core:index" via ROUTE_CORE_INDEX (url "/") so just wanted to make sure this change was intended.

[thekaveman]

Yes, thanks for noticing this and asking.

I did intentionally make this change because it seemed wrong to direct the user to core:index if they had an agency selected already.

[thekaveman]

I think it would be good if @angela-tran takes a look before this is merged.

[angela-tran]

This refactor looks good to me. I left a question about how the routes context processor works, which I think is more just for my understanding rather than pointing out a needed change.