Add unittests

[sdobbert]

Description

This adds Unittest for some components where they were previously missing.

Related issues or pull requests

Pull request type

• Bugfix
• Feature
• Dependency updates
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe)

Do you introduce a breaking change?

• Yes
• No

Checklist

• I understand and agree that the changes in this PR will be licensed under the
  BSD-2-Clause.
• I have followed the guidelines for contributing.
• The proposed change fits to the content of the Code of Conduct.
• I have added or updated tests and documentation, and the test suite passes (run npm run check locally).
• I have added a screenshot/screencast to illustrate the visual output of my update.

[marcjansen]

This looks great. Please merge, and then try to pick additional tests (if any) from #4394

That also has some changes to components, so I think there is some value in the other PR.

Please go ahead and pick whatever you think is good from my PR.

[dnlkoch]

🎉 This PR is included in version 32.3.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀