[builder] additional unit tests for builder

[bkmartinjr]

Changes:

• More coverage of build() tests, including all supported X array formats
• add explicit test of the data copy (to s3) functions

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.98%. Comparing base (f2d19a7) to head (c3ccd92).
Report is 1 commits behind head on main.

❗ Current head c3ccd92 differs from pull request most recent head bc329e2. Consider uploading reports for the commit bc329e2 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1085      +/-   ##
==========================================
+ Coverage   90.65%   90.98%   +0.33%     
==========================================
  Files          76       77       +1     
  Lines        5873     5926      +53     
==========================================
+ Hits         5324     5392      +68     
+ Misses        549      534      -15     

Flag	Coverage Δ
unittests	90.98% <100.00%> (+0.33%)	⬆️

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[prathapsridharan]

LGTM