add test case for unit prop

[raffifu]

This PR resolve #605

When adding test case, i still can't figured it out how to trigger repr function. Could you help me with guidance to trigger that?

Improvement

[coveralls]

Pull Request Test Coverage Report for Build 9468404219

Details

• 15 of 15 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.5%) to 97.246%

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Totals
Change from base Build 9241523599:	0.5%
Covered Lines:	2790
Relevant Lines:	2869

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💛 - Coveralls

[niccokunzmann]

@raffifu, you can use repr() on the object.
Thanks for your contribution!

[niccokunzmann]

Would you like to add improve test coverage to the changelog in your PR?

[raffifu]

@niccokunzmann i already add improve test code into changelog

[niccokunzmann]

@raffifu Thanks for this PR!