test: add test to log_writer and meter

[mmta]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 96.77419% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 95.47%. Comparing base (1e18996) to head (334170a).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #38      +/-   ##
==========================================
+ Coverage   93.88%   95.47%   +1.58%     
==========================================
  Files          27       27              
  Lines        5529     5588      +59     
==========================================
+ Hits         5191     5335     +144     
+ Misses        338      253      -85     

Flag	Coverage Δ
unittests	95.47% <96.77%> (+1.58%)	⬆️

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Files	Coverage Δ
server/src/log_writer.rs	90.14% <100.00%> (+6.41%)	⬆️
server/src/meter.rs	98.36% <93.93%> (+93.96%)	⬆️