fix repca, add unittest

[behinger]

Related issues

Closes #

Checklist

• Tests are passing
• Lint workflow is passing
• Docs were updated and workflow is passing

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.16%. Comparing base (c629b29) to head (7221ead).

Files with missing lines	Patch %	Lines
src/statistics.jl	50.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #21      +/-   ##
==========================================
+ Coverage   92.26%   94.16%   +1.90%     
==========================================
  Files           8        8              
  Lines         362      360       -2     
==========================================
+ Hits          334      339       +5     
+ Misses         28       21       -7     

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