test: Fix UTC assuming test

[BYK]

Fixes #3720.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.28%. Comparing base (ce9986c) to head (b79350a).
Report is 2 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3722   +/-   ##
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  Coverage   84.28%   84.28%           
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  Files         133      133           
  Lines       14261    14261           
  Branches     2405     2405           
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  Hits        12020    12020           
  Misses       1490     1490           
  Partials      751      751           

see 2 files with indirect coverage changes

[asottile-sentry]

given the comment I actually think the implementation is incorrect and should be something like:

try:
   dt = datetime.fromisoformat(s)
except ...:
    ...
else:
   if dt.tzinfo is None:
       return dt.replace(tzinfo=UTC)
   else:
       return dt.astimezone(UTC)

[BYK]

I wrote that comment 😅 And after reading the ISO 8601 spec, I think I was mistaken:

https://en.wikipedia.org/wiki/ISO_8601#Local_time_(unqualified)

If no UTC relation information is given with a time representation, the time is assumed to be in local time.

Now there's the obvious warning this being unsafe in the next sentence but I'm split between being spec-compliant or "doing the right thing" which may confuse people if they rely on the spec.

What's your take @asottile-sentry?

[asottile-sentry]

I suspect it won't matter as most should run their servers in UTC anyway -- so I guess we can go with the current implementation

it seems to only be used to sort breadcrumbs in the event payload (is that even necessary? surely relay or the frontend should sort those right? do we even need this function and the caller?)

[BYK]

surely relay or the frontend should sort those right?

Agree with this but maybe we're trying to save resources? It also seems like the side effect of converting a string to a python date might be something we are after here. That said that python date will then be converted back into an ISO 8601 timestamp so 🤷🏻

Will ask ingest folks.

[asottile-sentry]

maybe we can just delete this code?