tests: Add unit tests for repeated_chars_iterator

[RaduNichita]

Added two more unit tests to the suite:

• one to test the std::next function on a beman iterator
• one to test the std::distance function on a beman iterator

[camio]

Could these tests be made constexpr with static_assert?

[steve-downey]

constexpr can involve different code paths in the implementation, so the tests should generally be both consteval and runtime. I think?

I'm still working out understanding of constexpr testing and testing constexpr code.

[neatudarius]

I would also add tests for concepts like in https://github.com/beman-project/optional26/blob/main/src/beman/optional26/tests/detail/iterator.t.cpp

[neatudarius]

constexpr can involve different code paths in the implementation, so the tests should generally be both consteval and runtime. I think?

I'm still working out understanding of constexpr testing and testing constexpr code.

https://github.com/beman-project/optional26/blob/main/src/beman/optional26/tests/detail/iterator.t.cpp#L18C9-L18C28

@steve-downey , is the same solution that we already have in this file in optional26? Is there any other "better" utility?

[steve-downey]

constexpr can involve different code paths in the implementation, so the tests should generally be both consteval and runtime. I think?

I'm still working out understanding of constexpr testing and testing constexpr code.

https://github.com/beman-project/optional26/blob/main/src/beman/optional26/tests/detail/iterator.t.cpp#L18C9-L18C28

@steve-downey , is the same solution that we already have in this file in optional26? Is there any other "better" utility?

Looking at that, I'm not 100% sure that's actually consteval? That macro looks like it would work in a constexpr context, but it would also work at runtime?
Also need to be sure that, for example, we could iterate an array in a consteval function using one of these? Or a constexpr vector, if the compiler will let us?
And, hopefully, still produce a junit report so the dashboard is green, or the appropriate test is visibly failing?

Failing to compile is a draconian error and we don't get any other test results.

[neatudarius]

Link this PR against #5