StaticResource only matches folder-like URL prefix

[danking]

What do these changes do?

I think this fixes #5250.

A static resource like:

routes.static('/foo', '/www/foo')

currently matches /foobar but returns 404. This PR ensures that aforementioned static route does not match /foobar

Are there changes in behavior for the user?

If a user expected /foobar to load the file /www/foo/ar, this PR will violate their expectation.

Related issue number

Fixes #5250

Checklist

I'm not aware of any docs that need to change, but I didn't tick that box because I am not certain.

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
• If you provide code modification, please add yourself to CONTRIBUTORS.txt
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[Dreamsorcerer]

The fact that /foobar is translated to /ar seems surprising, so I'd be inclined to say that it's unlikely that people are depending on this behaviour. Though it could be possible that someone uses paths like /static-filename...

I wonder if the prefix argument should be renamed to path though, to avoid confusion if we do change it...

[codecov]

Codecov Report

Merging #5534 (519539b) into master (9220703) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #5534   +/-   ##
=======================================
  Coverage   93.31%   93.31%           
=======================================
  Files         102      102           
  Lines       30313    30325   +12     
  Branches     2723     2724    +1     
=======================================
+ Hits        28287    28299   +12     
  Misses       1849     1849           
  Partials      177      177           

Flag	Coverage Δ
unit	93.24% <100.00%> (+<0.01%)	⬆️

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Impacted Files	Coverage Δ
aiohttp/web_urldispatcher.py	97.55% <100.00%> (+<0.01%)	⬆️
tests/test_web_urldispatcher.py	98.14% <100.00%> (+0.07%)	⬆️

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[danking]

OK, I’m fairly certain this is ready for review. Again, I don’t think the docs need to change because I think of this as a bug fix, but I’m not sure.

[Dreamsorcerer]

@webknjaz Thoughts on this? Seems to resolve some surprising behaviour.
But, looks like it also adds a little overhead, which I assume is running on every request.

Maybe a more efficient solution would be to ensure that that static resource is always at the end of the list, so it's the last one checked? This sounds reasonable to me, as a web server should be handling static assets on a production system where performance matters, therefore the static resource would never be useful.

[webknjaz]

@Dreamsorcerer I'm not sure about that. Making the priority assumptions should probably be on the user. Besides, this would be a breaking change for people who used to rely on the order.

[patchback]

Backport to 3.8: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.8/9c7f3d37fd9ad2aea4d7f382062d52dca9d2bd89/pr-5534

Backported as #6179

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