Update reverse-string missing test cases

[Elahi-cs]

As mentioned by @BNAndras in #775 , some of reverse-string's test cases were created after opening the issue. This PR adds the missing test cases.

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[vaeng]

I'm pretty sure there is a discussion about this exercise with @siebenschlaefer somewhere.
I think the final consent was to not include the grapheme-based tests, as they are painful to implement in c++14 (and probably still are for c++23).

Maybe it was on the forums?

[BNAndras]

Julia hides the grapheme tests behind a flag the student needs to set so that might be an option here. That'd require the example solution to be reworked.

[vaeng]

Julia hides the grapheme tests behind a flag the student needs to set so that might be an option here. That'd require the example solution to be reworked.

Great idea. I like that. We could hide it with compiler flag option and describe the how-to in .docs/introduction.append.md. Marked as an additional challenge, it would not even interfere with the test runner.

[Elahi-cs]

@vaeng should I try to make these changes to the test cases to hide them behind a compiler flag in this same pull request? Could you elaborate as to how that wouldn't interfere with the test runner?

[vaeng]

Do you understand how the EXERCISM_RUN_ALL_TESTS flag is used?

We could have a similar flag, like ADVANCED_STRING_TESTS and describe the usage and reasoning in an .append.md for expert students.

You do have to use this PR for both, as the CI checks will not run otherwise and they make a logical group for a PR.

(Also you need some code formatting to pass the other check).

Do you need help for these?

[Elahi-cs]

Do you understand how the EXERCISM_RUN_ALL_TESTS flag is used?

We could have a similar flag, like ADVANCED_STRING_TESTS and describe the usage and reasoning in an .append.md for expert students.

I do! I just have a question: Would EXERCISM_RUN_ALL_TESTS include all tests in this case? Or would both EXERCISM_RUN_ALL_TESTS and ADVANCED_STRING_TESTS need to be used to run both the tests and the grapheme cluster tests?

You do have to use this PR for both, as the CI checks will not run otherwise and they make a logical group for a PR.

(Also you need some code formatting to pass the other check).

Do you need help for these?

That makes sense! I'll get on that then. I'll let you know if I have any further questions, thank you for your guidance.

[vaeng]

Would EXERCISM_RUN_ALL_TESTS include all tests in this case? Or would both EXERCISM_RUN_ALL_TESTS and ADVANCED_STRING_TESTS need to be used to run both the tests and the grapheme cluster tests?

If you want to be clean, you can edit the example files in the .meta directory, to be able to solve the added cases. In that case you would also need to edit the CMakeLists.txt to set the new ADVANCED_STRING_TESTS flag - here:

cpp/exercises/practice/reverse-string/CMakeLists.txt

Line 54 in 9bd3753

target_compile_definitions(${exercise} PRIVATE EXERCISM_RUN_ALL_TESTS)

With the edited CMakeLists.txt the test-runner will see your added code. If you don't set the flag, it won't notice the difference.

Moving the advanced tests outside the EXERCISM_RUN_ALL_TESTS group does not really make a difference. To have it a bit cleaner, I would have them below in an extra grouping, anyway.

[vaeng]

Are you still working on this, or do you want me to finish your work @Elahi-cs

[Elahi-cs]

Are you still working on this, or do you want me to finish your work @Elahi-cs

I'm really sorry for the very late reply @vaeng, I will not have time for it anymore.

[vaeng]

@ahans @siebenschlaefer

Do you think the append will suffice?

[BNAndras]

Neither graphemes nor code points are introduced before this sentence. An external link here might be useful as background info.

[BNAndras]

Unicode is not introduced before this sentence. I'd similarly recommend an external link and perhaps a framing sentence about how Unicode is relevant before diving into the technical details.

[ahans]

Suggested change

	You can try them out by setting the `TEST_GRAPHEMES` compiler flag or editing the test file accordingly.
	You can try them out by setting the `TEST_GRAPHEMES` preprocessor define or editing the test file accordingly.

[ahans]

To me this sounds reasonable, but @BNAndras's points are valid. Having a few more external references probably wouldn't hurt.

However, what I'm missing most here is something about how to approach this in C++. Simply using something like std::u16string won't work, since in the test cases we clearly use UTF-8. Are students expected to implement some UTF-8 handling themselves? Can they use some library?