BUG: fix __doctest_requires__ when constraint is present

[KostaIlic2]

Fix #318.

Also improved related unit test.

[KostaIlic2]

Tests passed. Do you wish to take this out of draft? Thanks! :)

@pllim, Thank you for all your support. I took the PR out of draft.

I noticed that you changed the milestone to 1.7.1. Do we need to change the first line of the changelog to 1.7.1 instead of 1.8.0?

[pllim]

Do we need to change the first line of the changelog to 1.7.1 instead of 1.8.0?

I think that is at the discretion of the release manager. I feel like this is a bug and should land in a bugfix release if the next release does not contain new feature. It is not something we should worry about in this PR.

[pllim]

@bsipocz are you able to review the internal code changes or ping someone who can? Thanks!

[bsipocz]

This all looks good, and I like that you added comprehensive case coverage for the test.

[bsipocz]

Thank you @KostaIlic2!

[KostaIlic2]

This all looks good, and I like that you added comprehensive case coverage for the test.

@bsipocz, Thank you for the feedback! And thank you for your speedy responses and support!