Add some tests for parentPath/basename

[mjcarroll]

Verify the behavior of parentPath and basename in ign-common4 to assert that #308 is correct.

[codecov]

Codecov Report

Merging #309 (918e8d4) into ign-common4 (bde2937) will not change coverage.
The diff coverage is n/a.

❗ Current head 918e8d4 differs from pull request most recent head 20c0154. Consider uploading reports for the commit 20c0154 to get more accurate results

@@             Coverage Diff              @@
##           ign-common4     #309   +/-   ##
============================================
  Coverage        77.02%   77.02%           
============================================
  Files               76       76           
  Lines            10729    10729           
============================================
  Hits              8264     8264           
  Misses            2465     2465           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update bde2937...20c0154. Read the comment docs.

[chapulina]

LGTM with happy CI.

Note that the absolute parentPath test is having different results for Windows on this branch and on main with #308

• Here: EXPECT_EQ(parentPath(absolute), "home\\bob")
• On main: EXPECT_EQ(parentPath(absolute), "\\home\\bob")

If we consider the behaviour on this branch to be correct (since it's a stable version), then a fix should go into main later. Otherwise, if we think this branch is wrong, we could change the behaviour here and document it in the migration guide (but that may affect users).