ref: profile sample mocking

[armcknight]

This is the last component of a long-standing desire to mock components of the profiler. It extracts the objc++ code from SentryProfilerTests.mm into an interface that can be used from Swift tests as well. This will help write finer grained tests to validate an upcoming fix, as well as speed up the profiler tests.

#skip-changelog

[codecov]

Codecov Report

Merging #3133 (b9c22e6) into main (596ccc1) will decrease coverage by 0.015%.
The diff coverage is 100.000%.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #3133       +/-   ##
=============================================
- Coverage   89.109%   89.094%   -0.015%     
=============================================
  Files          501       501               
  Lines        53920     53901       -19     
  Branches     19294     19297        +3     
=============================================
- Hits         48048     48023       -25     
- Misses        4902      5018      +116     
+ Partials       970       860      -110     

Impacted Files	Coverage Δ
...ts/SentryTests/Transaction/SentryTracerObjCTests.m	100.000% <ø> (ø)
Sources/Sentry/SentryProfiler.mm	78.086% <100.000%> (+0.204%)	⬆️
...SentryProfilerTests/SentryProfilerSwiftTests.swift	97.063% <100.000%> (+0.030%)	⬆️
Tests/SentryProfilerTests/SentryProfilerTests.mm	98.235% <100.000%> (-0.494%)	⬇️

... and 27 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 596ccc1...b9c22e6. Read the comment docs.

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1249.16 ms	1251.47 ms	2.31 ms
Size	22.84 KiB	401.67 KiB	378.83 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
561fa74	1243.27 ms	1260.62 ms	17.35 ms
aa27ac0	1214.02 ms	1227.42 ms	13.40 ms
369222e	1232.14 ms	1258.90 ms	26.76 ms
d80d410	1231.50 ms	1240.14 ms	8.64 ms
a6f8b18	1238.54 ms	1265.56 ms	27.02 ms
dacf894	1223.96 ms	1250.41 ms	26.45 ms
189b629	1245.53 ms	1270.06 ms	24.53 ms
e84bc3f	1201.49 ms	1232.82 ms	31.33 ms
adca747	1250.82 ms	1267.57 ms	16.76 ms
32e64d1	6272.19 ms	6299.50 ms	27.31 ms

App size

Revision	Plain	With Sentry	Diff
561fa74	20.76 KiB	427.23 KiB	406.46 KiB
aa27ac0	20.76 KiB	432.21 KiB	411.45 KiB
369222e	20.76 KiB	419.67 KiB	398.91 KiB
d80d410	20.76 KiB	425.71 KiB	404.95 KiB
a6f8b18	20.76 KiB	431.87 KiB	411.11 KiB
dacf894	20.76 KiB	426.34 KiB	405.58 KiB
189b629	20.76 KiB	399.69 KiB	378.93 KiB
e84bc3f	20.76 KiB	434.72 KiB	413.96 KiB
adca747	20.76 KiB	401.36 KiB	380.60 KiB
32e64d1	20.76 KiB	433.18 KiB	412.42 KiB

Previous results on branch: armcknight/ref/profiler-mocks

Startup times

Revision	Plain	With Sentry	Diff
9a0bc46	1230.22 ms	1245.10 ms	14.88 ms
bc09ac9	1251.90 ms	1256.08 ms	4.19 ms
c8f477d	1246.22 ms	1263.82 ms	17.60 ms

App size

Revision	Plain	With Sentry	Diff
9a0bc46	22.84 KiB	401.67 KiB	378.83 KiB
bc09ac9	22.84 KiB	401.67 KiB	378.83 KiB
c8f477d	22.84 KiB	401.67 KiB	378.83 KiB

[brustolin]

All good but one file that seems to be in the wrong place.

[philipphofmann]

This ref improves the testability of the profiling code 💪 . Excellent. I'm only not approving cause of Dhiogo's comment #3133 (comment).

[philipphofmann]

Way cleaner 💯

[philipphofmann]

l: Mocks are usually test doubles that simulate the behavior of a real object with the added ability to verify interactions with that object. They are used to set expectations and assert that specific methods or properties of the mocked object are called or accessed correctly during testing. What you define here is a fake. Fakes are simplified implementations of a real object that mimics its behavior to some extent. They are typically used to provide a functional substitute for a real object that is too complex, slow, or unavailable for testing.

TLDR; if you want to follow the correct testing naming terms, we should rename all the mocks in this PR to fake, but I'm also fine with keeping it. I don't want to be nitpicking on testing terms.

[armcknight]

Sorry but I think this is more of a mock. I think we should be careful introducing too much terminology (and therefore cognitive overhead) like fixture, double, oracle, stub, mock, fake, dummy, spy, robot... I don't think these are all standardized terms in industry.

Since this is just creating structs to use as input to a real implementation, and not actually providing an alternate implementation of an interface, there is really no doubling going on at all, so in an OOP sense, this is neither mocking nor stubbing (nor faking).

I think the intention of the code gets across so I'm hesitant to change it. We're providing predefined input to the SUT and testing the output of the system.

[philipphofmann]

Fine by me 👍 .

[philipphofmann]

LGTM