fix(schema): use scule types for runtimeConfig type hints

[luc122c]

🔗 Linked issue

Resolves #23246

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

In the original code, if the first character was a digit, the code was adding an underscore before the character and then converting it to uppercase. This was causing the additional underscores when the input string was already in upper snake case.

TypeScript Playground link

This PR also adds a couple of tests to catch values already in upper snake case (as in the original issue).

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

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[danielroe]

Thank you ❤️

[danielroe]

Would you check the type fixture failures? 🙏

[luc122c]

The error that was being thrown was saying that the toEqualTypeOf function required one parameter with a type of 'never'. It seems a bit hacky, but by providing it with a value of [][0], the first value in an empty array, the error went away and the test runs as expected.

[danielroe]

I believe that is how the type assertion indicates there is a mismatch. This is what the mismatch looks like:

[luc122c]

Oh, interesting. I wasn't seeing any errors in the console output so I didn't think the tests were failing. I'll take another look.

[luc122c]

@danielroe I've changed the input for the last test that was failing. It was originally baseAPIToken, now baseApiToken, and I understand why this was struggling. Although we know that 'API' is a common acronym, TypeScript doesn't. It would be possible to add a case to check for this, however I think it may be more beneficial to correctly handle camelCase than to correctly handle this particular case? Please let me know your thoughts.

[danielroe]

The intent is to split the string with _ immediately before the final capital letter of a sequence of capital letters. So:

abcDEFghi => abc_DE_FGHI
abcDefGhi => ABC_DEF_GHI

This should be achievable in TS.

[luc122c]

The intent is to split the string with _ immediately before the final capital letter of a sequence of capital letters.

Ok, i've implemented this change.

baseAPIToken now becomes BASE_API_TOKEN however APP_NAMES, which is already correct, now becomes A_PP_NAME_S which was a case highlighted in the original issue.

[luc122c]

@danielroe Some of these test cases may not be possible with the current logic. For example, TESTAppName I can't figure out a way for this to work, since TypeScript doesn't know that 'Test', 'App' and 'Name' are words, so it doesn't know to split 'TESTA' before the A.

[danielroe]

The logic isn't related to whether they are words. Note that scule splits these all correctly; it's based on splitting before the change of case.

I think we can use scule's native types for this - but we should ideally expose them upstream.

[luc122c]

The logic isn't related to whether they are words. Note that scule splits these all correctly; it's based on splitting before the change of case.

This is the closest I've managed to get separately, just following the logic.

I think we can use scule's native types for this - but we should ideally expose them upstream.

Does Scule expose itself as a type, like Defu does?

[danielroe]

No - see unjs/scule#58. I pushed a change in c5f9a49 (#23696) that uses the inferred return type of snakeCase, however.

[luc122c]

No - see unjs/scule#58. I pushed a change in c5f9a49 (#23696) that uses the inferred return type of snakeCase, however.

Brilliant, this will be a much cleaner solution 👏

[codecov-commenter]

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