Add mirroring fraction edge case test

[tataruty]

Proposed changes

Noticed that there is no test for mirroring with Faction setting when Denominator=Numerator, when we get 100% mirroring

Closes #ISSUE

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

NONE

[tataruty]

@bjee19 please take a look if I missed and you already have it

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.03%. Comparing base (385d5be) to head (501f496).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3708      +/-   ##
==========================================
+ Coverage   87.00%   87.03%   +0.02%     
==========================================
  Files         128      128              
  Lines       15919    15919              
  Branches       62       62              
==========================================
+ Hits        13851    13855       +4     
+ Misses       1902     1899       -3     
+ Partials      166      165       -1     

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[bjee19]

lgtm, nice catch