Add type hints to `tests`

[codecov[bot]]

Codecov Report

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

Project coverage is 93.18%. Comparing base (4964129) to head (2ac605e). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #41 +/- ## ========================================== + Coverage 93.09% 93.18% +0.08% ========================================== Files 50 49 -1 Lines 2043 2069 +26 Branches 296 293 -3 ========================================== + Hits 1902 1928 +26 Misses 118 118 Partials 23 23 ```

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