Use Mocha in Tests

[Quantalabs]

Checklist:

• [x] Title is meaningful
• [x] Followed Contributing Guidelines
• [x] No new issues, pre-existing issues in the repo are okay. We just don't want faulty code to be published to the nightly build or main if it can be prevented
• [x] All new dependencies are added to [package.json]

Overview

Adds mocha and istanbul to testing, and up code coverage to 100%.

Other Notes

Closes #121

[codecov[bot]]

Codecov Report

:exclamation: No coverage uploaded for pull request base (main@31848da). Click here to learn what that means. The diff coverage is n/a.

@@           Coverage Diff            @@
##             main      #130   +/-   ##
========================================
  Coverage        ?   100.00%           
========================================
  Files           ?         5           
  Lines           ?       453           
  Branches        ?         0           
========================================
  Hits            ?       453           
  Misses          ?         0           
  Partials        ?         0           

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