Fix unit tests

[soininen]

Re spine-tools/Spine-Toolbox#2294

Checklist before merging

• [x] Unit tests have been added/updated accordingly
• [x] Code has been formatted by black
• [x] Unit tests pass

[codecov-commenter]

Codecov Report

:exclamation: No coverage uploaded for pull request base (0.8-dev@7a6c596). Click here to learn what that means. Patch has no changes to coverable lines.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## 0.8-dev #157 +/- ## ========================================== Coverage ? 55.46% ========================================== Files ? 192 Lines ? 17286 Branches ? 2829 ========================================== Hits ? 9587 Misses ? 7179 Partials ? 520 ```

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