Convert tidier.js to TypeScript && test coverage of tidier.ts

[kashish00208]

Fixes #3815 #3816

Changes:
This PR implements the following changes based on issue #3816 #3815:

1. Rename and TypeScript conversion:
   1. Renamed tidier.js → tidier.ts.
   2. Added TypeScript types for the CodeMirror view, the mode argument, and other values flagged during conversion.
   3. Updated necessary imports/exports.
2. Functionality verification:
   1. Manually verified that Tidy and Format works correctly for JavaScript, HTML, and CSS files.
   2. Ensured that when formatting the editor content, the cursor remains stable and does not jump unexpectedly.
3. Integration tests:
   1. Added tests for tidier.ts
   2. Using “Tidy Code” updates the editor document with Prettier formatting.
   3. Cursor position remains stable and predictable after formatting.
   4. Formatting works for HTML, JavaScript, and CSS files.
   5. Tests focus only on integration behavior, not Prettier internals.

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• has no typecheck errors (npm run typecheck)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #123
• meets the standards outlined in the accessibility guidelines

[raclim]

Thanks so much for your work! This looks great so far!

We recently merged in a PR that added tests for tidier.js as a JavaScript file—would you be open to updating this PR with the changes from the develop-codemirror-v6 branch, convert that test to TypeScript, and also add in any additional updates to the test that you think would be beneficial?

[kashish00208]

Thanks so much for your work! This looks great so far!

We recently merged in a PR that added tests for tidier.js as a JavaScript file—would you be open to updating this PR with the changes from the develop-codemirror-v6 branch, convert that test to TypeScript, and also add in any additional updates to the test that you think would be beneficial?

I've updated the PR! I merged the latest changes from develop-codemirror-v6, deleted the JS test file, and fully migrated the suite to TypeScript. I also added the beneficial tests for empty documents and cursor stability do let me know if any chnages needed .

[raclim]

Thanks so much for the updates! I think these feel overall good to me—also tagging @khanniie for review!

[khanniie]

Overall looking super solid! Thank you so much, this is great! Just a few tiny comments

[khanniie]

Small nit but I'm not sure I understand why one type is capitalized and the other isn't! For consistency with the style guide maybe we can call this one ParserTypes?

[khanniie]

for this test, can we can test for the fully properly formatted JavaScript? I don't think this exactly tests for the correctness of the formatter. You should be able to include new lines (\n) in the test string

[khanniie]

Same here can we test for the fully properly formatted output?

[khanniie]

Here too

[kashish00208]

@khanniie thank you pointing it out I've updated the tests to be more rigorous. Instead of using .toContain(), I switched to .toBe() to verify the exact output from Prettier .