Added test for table copy method

[AlexMuresan]

[x] Wrote test for feature
[ ] Added changes to CHANGELOG.md
[ ] Bumped version number (delete if unneeded)

Changes proposed:
Test for Table copy method

Tests that a deep copy is not changed when original table is changed Tests that a shallow copy is changed when the original table is changed

[adnanhemani]

Hi, thank you for this - but we already have a test for shallow copy vs regular copy as part of the doctests in the code itself. So this addition to the test suite is not really required. If you feel differently, please let me know why this adds value. Thanks!