test Lint() in test-Lint

[MichaelChirico]

Successor/companion to #2142

This paves the way for lint() to be tested in this file, test-lint.R. But combining the two squashes the history that's important to keep (test-Lint used to be test-lint, and next test-lint used to be test-lint_file).

[codecov-commenter]

Codecov Report

Merging #2145 (6560e4d) into main (203be65) will not change coverage.
The diff coverage is n/a.

❗ Current head 6560e4d differs from pull request most recent head da5dbe0. Consider uploading reports for the commit da5dbe0 to get more accurate results

@@           Coverage Diff           @@
##             main    #2145   +/-   ##
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  Coverage   99.64%   99.64%           
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  Files         112      112           
  Lines        5125     5125           
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  Hits         5107     5107           
  Misses         18       18