test: missing domain tests for storage boxes types

[jooola]

• Test equality for the storage box type domain.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.32%. Comparing base (e064c26) to head (2a16000).
⚠️ Report is 53 commits behind head on storage-boxes.

Additional details and impacted files

@@              Coverage Diff               @@
##           storage-boxes     #530   +/-   ##
==============================================
  Coverage          96.32%   96.32%           
==============================================
  Files                 70       70           
  Lines               3153     3153           
==============================================
  Hits                3037     3037           
  Misses               116      116           

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