Add registry service tests

[qwerty287]

built on top of the test from #6252

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 33.80%. Comparing base (26a01ec) to head (9a18d9c).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6330      +/-   ##
==========================================
+ Coverage   33.32%   33.80%   +0.48%     
==========================================
  Files         420      420              
  Lines       28333    28333              
==========================================
+ Hits         9441     9578     +137     
+ Misses      18014    17862     -152     
- Partials      878      893      +15     

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