Slightly better netlink client tests

[nbrownus]

Provides better test-ability and error messages in tests that fail for the NetlinkClient

[codecov-io]

Codecov Report

Merging #35 into master will decrease coverage by 0.38%.
The diff coverage is 25%.

@@            Coverage Diff             @@
##           master      #35      +/-   ##
==========================================
- Coverage   75.04%   74.66%   -0.39%     
==========================================
  Files           5        5              
  Lines         589      592       +3     
==========================================
  Hits          442      442              
- Misses        133      136       +3     
  Partials       14       14

Impacted Files	Coverage Δ
audit.go	75.54% <0%> (-0.84%)	⬇️
client.go	88.37% <50%> (ø)	⬆️

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[alanhlam]

👍