test(profiling): reproduce root span tracking issue

[armcknight]

#skip-changelog

trying to repro a failure mode that was fixed in #5063 so we can have a unit test for it. it needs to integrate SentryTimeToDisplayTracker and SentryUIViewControllerSwizzling and related subsystems together with launch profiling.

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1229.65 ms	1240.80 ms	11.14 ms
Size	22.30 KiB	844.41 KiB	822.11 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
9854a57	1230.02 ms	1252.78 ms	22.75 ms
eaa1002	1205.50 ms	1235.08 ms	29.58 ms
596ccc1	1214.98 ms	1239.36 ms	24.38 ms
326b7eb	1223.41 ms	1235.66 ms	12.25 ms
51307b7	1223.08 ms	1240.76 ms	17.68 ms
84972e4	1220.10 ms	1243.25 ms	23.15 ms
cc0f809	1231.63 ms	1254.26 ms	22.63 ms
96af87c	1228.76 ms	1242.27 ms	13.51 ms
6230686	1219.06 ms	1244.47 ms	25.41 ms
bf809be	1221.58 ms	1239.85 ms	18.27 ms

App size

Revision	Plain	With Sentry	Diff
9854a57	21.90 KiB	727.72 KiB	705.82 KiB
eaa1002	20.76 KiB	423.19 KiB	402.43 KiB
596ccc1	22.84 KiB	401.44 KiB	378.60 KiB
326b7eb	20.76 KiB	432.31 KiB	411.55 KiB
51307b7	22.85 KiB	407.63 KiB	384.78 KiB
84972e4	21.58 KiB	637.65 KiB	616.06 KiB
cc0f809	22.31 KiB	768.14 KiB	745.83 KiB
96af87c	21.58 KiB	654.58 KiB	633.00 KiB
6230686	21.90 KiB	708.34 KiB	686.44 KiB
bf809be	22.30 KiB	821.87 KiB	799.56 KiB

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 8.892%. Comparing base (53e4168) to head (4f08abe).

❗ There is a different number of reports uploaded between BASE (53e4168) and HEAD (4f08abe). Click for more details.

HEAD has 2 uploads less than BASE

Flag	BASE (53e4168)	HEAD (4f08abe)
	3	1

Additional details and impacted files

@@              Coverage Diff              @@
##              main    #5071        +/-   ##
=============================================
- Coverage   92.711%   8.892%   -83.820%     
=============================================
  Files          674      358       -316     
  Lines        83514    25730     -57784     
  Branches     30409       94     -30315     
=============================================
- Hits         77427     2288     -75139     
- Misses        5989    23442     +17453     
+ Partials        98        0        -98     

Files with missing lines	Coverage Δ
...entry/Profiling/SentryProfiledTracerConcurrency.mm	9.677% <ø> (-82.062%)	⬇️

... and 665 files with indirect coverage changes

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[philipphofmann]

m: As you pointed out on Slack, you want to have input on that test. I think we could make our lives easier here by limiting the setup and dependencies we require for testing. Ideally, yes we test with the started SDK, an UIViewController to start and finish a trace, but if this causes trouble, we can also emulate what that code is doing by directly interacting with the code we want to test.
If the code we want to test requires all the setup, we could try to refactor the code so it is easier to test. I'm sorry it's a bit hard to explain in GH comment what exactly would be required here.

[armcknight]

Yes, I tried initially starting with just the components I had in mind, things kept failing in weird ways due to the tightly coupled nature of many parts of the SDK.

[philipphofmann]

Maybe we can refactor parts of the code we want to test so it depends on less code.