Test cov minibatch

[MatthewSZhang]

Checklist

• Used a personal fork to propose changes
• A reference to a related issue: TST RuntimeError in minibatch not covered in test #251
• A description of the changes: add unit test to cov minibatch runtime error

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (0b3928d) to head (b60fc0a).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #252      +/-   ##
===========================================
+ Coverage   99.70%   100.00%   +0.29%     
===========================================
  Files          11        11              
  Lines        1001      1001              
===========================================
+ Hits          998      1001       +3     
+ Misses          3         0       -3     

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