add sendmsg/recvmsg test

[loongs-zhang]

// Describe your PR here; eg. Fixes #issueNo

Make sure that:

• You submit test cases (unit or integration tests) that back your changes.
• Your local test passed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.62%. Comparing base (55f4d1d) to head (4f20e48).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #368      +/-   ##
==========================================
+ Coverage   71.02%   74.62%   +3.59%     
==========================================
  Files          68       68              
  Lines        5367     5367              
==========================================
+ Hits         3812     4005     +193     
+ Misses       1555     1362     -193     

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