Remove duplicate union test

[codecov[bot]]

Codecov Report

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

Project coverage is 89.97%. Comparing base (4aa8264) to head (be0ec94). Report is 9 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #225 +/- ## ========================================== + Coverage 89.58% 89.97% +0.39% ========================================== Files 11 11 Lines 1844 1896 +52 ========================================== + Hits 1652 1706 +54 + Misses 192 190 -2 ```

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