Support checking multiple requirements

[shizmob]

This patchset changes the router to be able to handle multiple requirements.
It does this by adding a small change to the matching core to iterate over the requirements instead of doing a direct match,
and by making a change to the group merging logic: instead of the presence of absence of requirements, it will check for a potential overlap in the keys being checked. If there is no overlap, there's a potential for ambiguous handlers, so we need to reject it.

As a side-effect, this also now allows the router to match situations like this:

@app.get('/foo')
def handler1(request):
    ...

@app.get('/foo', requirements={'a': 42})
def handler2(request):
    ...

Where handler1 will be invoked if a is unset or not 42, and handler2 if it is.

[ahopkins]

As a side-effect, this also now allows the router to match situations like this:

Where handler1 will be invoked if a is unset or not 42, and handler2 if it is.

How will it handle a = 41?

[shizmob]

How will it handle a = 41?

This matches the or not 42 case, so it will invoke handler1.

[ahopkins]

@shizmob What is the status of this?

[ahopkins]

@shizmob?

[shizmob]

Sorry, this issue completely dropped of my radar as I had to dedicate myself towards some other projects. Is there anything from your side that you'd like clarified or changed in this PR?

[ahopkins]

Excellent, thanks. Can you merge whatever latest is needed and mark as ready for review?

[shizmob]

Done! I added another change to the requirements, as pytest-flake8 exhibits compatibility issues with flake8 5: tholo/pytest-flake8#87. flake8 4.x seems to be broken on Python 3.12 though, so we may need to re-think the current approach to invoking flake8. Since we're already using black, does it make sense to drop it entirely?

[ahopkins]

Going to hold off on this until after the LTS goes out.