Add a test.File function for comparing expected file contents

[FollowTheProcess]

Description

Motivation and Context

Closes #

How Has This Been Tested?

Checklist

• I have updated the documentation if needed.
• I have updated the tests if needed.

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (0986fff) 96.20% compared to head (8fdc6db) 93.25%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #12      +/-   ##
==========================================
- Coverage   96.20%   93.25%   -2.95%     
==========================================
  Files           1        1              
  Lines          79       89      +10     
==========================================
+ Hits           76       83       +7     
- Misses          2        4       +2     
- Partials        1        2       +1     

Files	Coverage Δ
test.go	93.25% <70.00%> (-2.95%)	⬇️

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