[tests] add unittests for common/utils.cpp

[codecov-commenter]

Codecov Report

Merging #131 into master will increase coverage by 2.34%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #131      +/-   ##
==========================================
+ Coverage   62.62%   64.96%   +2.34%     
==========================================
  Files          52       52              
  Lines        4754     4755       +1     
==========================================
+ Hits         2977     3089     +112     
+ Misses       1777     1666     -111     

Impacted Files	Coverage Δ
src/common/utils.hpp	100.00% <100.00%> (ø)
src/library/commissioner_impl.cpp	73.98% <100.00%> (+0.03%)	:arrow_up:
src/library/joiner_session.hpp	84.61% <0.00%> (ø)
src/library/joiner_session.cpp	88.39% <0.00%> (+1.55%)	:arrow_up:
src/common/address.cpp	100.00% <0.00%> (+4.25%)	:arrow_up:
src/app/cli/interpreter.cpp	44.40% <0.00%> (+4.26%)	:arrow_up:
src/app/cli/console.cpp	86.95% <0.00%> (+10.03%)	:arrow_up:
src/common/utils.cpp	92.59% <0.00%> (+22.22%)	:arrow_up:
src/app/border_agent.cpp	80.14% <0.00%> (+25.73%)	:arrow_up:
src/app/cli/main.cpp	93.75% <0.00%> (+27.08%)	:arrow_up:
... and 1 more