Improve source helper test coverage

[kemsta]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 96.38095% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.95%. Comparing base (16f0149) to head (c5ab867).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
core_engine/src/sources/screen_capture.rs	92.02%	11 Missing ⚠️
core_engine/src/sources/app_audio.rs	91.42%	3 Missing ⚠️
core_engine/src/sources/synthetic.rs	98.63%	2 Missing ⚠️
core_engine/src/outputs/asr_sink.rs	98.24%	1 Missing ⚠️
core_engine/src/outputs/wav_file.rs	96.96%	1 Missing ⚠️
core_engine/src/sources/microphone.rs	97.05%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #16      +/-   ##
==========================================
+ Coverage   67.53%   68.95%   +1.42%     
==========================================
  Files          14       14              
  Lines        3767     5215    +1448     
==========================================
+ Hits         2544     3596    +1052     
- Misses       1223     1619     +396     

Flag	Coverage Δ
python	90.48% <ø> (+8.12%)	⬆️
rust	67.01% <96.38%> (+1.39%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.