Encoder tests

[levtelyatnikov]

Checklist

• My pull request has a clear and explanatory title.
• My pull request passes the Linting test.
• I added appropriate unit tests and I made sure the code passes all unit tests. (refer to comment below)
• My PR follows PEP8 guidelines. (refer to comment below)
• My code is properly documented, using numpy docs conventions, and I made sure the documentation renders properly.
• I linked to issues and PRs that are relevant to this PR.

Description

Issue

Additional context

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.62%. Comparing base (cf84728) to head (d3fe8be).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #115      +/-   ##
==========================================
+ Coverage   85.48%   87.62%   +2.14%     
==========================================
  Files         126      125       -1     
  Lines        3582     3547      -35     
==========================================
+ Hits         3062     3108      +46     
+ Misses        520      439      -81     

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