add unit tests for artifact mixin

[MichelleArk]

Resolves #

Problem

Solution

Checklist

• I have read the contributing guide and understand what's expected of me.
• I have run this code in development, and it appears to resolve the stated issue.
• This PR includes tests, or tests are not required or relevant for this PR.
• This PR has no interface changes (e.g., macros, CLI, logs, JSON artifacts, config files, adapter interface, etc.) or this PR has already received feedback and approval from Product or DX.
• This PR includes type annotations for new and modified functions.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.11%. Comparing base (407f6ca) to head (39dcb3f).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11050      +/-   ##
==========================================
- Coverage   89.15%   89.11%   -0.05%     
==========================================
  Files         183      183              
  Lines       23765    23765              
==========================================
- Hits        21188    21177      -11     
- Misses       2577     2588      +11     

Flag	Coverage Δ
integration	86.42% <ø> (-0.05%)	⬇️
unit	62.17% <ø> (ø)

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Components	Coverage Δ
Unit Tests	62.17% <ø> (ø)
Integration Tests	86.42% <ø> (-0.05%)	⬇️