Chore/68 add unit test

[datnguye]

resolves #68

Description

Fulfill unit test

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
• [x] This PR includes tests, or tests are not required/relevant for this PR
• [ ] I have opened an issue to add/update docs, or docs changes are not required/relevant for this PR

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (2ae1867) 85.60% compared to head (0ee6a32) 100.00%. Report is 7 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #82 +/- ## ============================================ + Coverage 85.60% 100.00% +14.39% ============================================ Files 31 31 Lines 910 915 +5 ============================================ + Hits 779 915 +136 + Misses 131 0 -131 ```

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