Docs: Maintenance > Bumping the Babel version

[JoshuaKGoldberg]

Before You File a Documentation Request Please Confirm You Have Done The Following...

• I have looked for existing open or closed documentation requests that match my proposal.
• I have read the FAQ and my problem is not listed.

Suggested Changes

Right now the @babel/* versions in our package.json are out of date, behind e.g. @babel/code-frame@7.18.6:

typescript-eslint/package.json

Lines 52 to 55 in 97d3e56

	"@babel/code-frame": "^7.16.7",
	"@babel/eslint-parser": "^7.18.2",
	"@babel/parser": "^7.18.0",
	"@babel/types": "^7.18.2",

I'm also seeing in fixtures-to-test.ts that there are some ignored fixture files due to previously filed Babel issues that have since been resolved:

typescript-eslint/packages/typescript-estree/tests/ast-alignment/fixtures-to-test.ts

Line 477 in 97d3e56

* @see https://github.com/babel/babel/issues/14613

typescript-eslint/packages/typescript-estree/tests/ast-alignment/fixtures-to-test.ts

Line 514 in 97d3e56

* @see https://github.com/babel/babel/issues/14589

When I update the @babel/* packages to latest, remove those ignores, and run typescript-estree tests, there are snapshot failures in typescript/expressions/instantiation-expression.src.ts. https://github.com/typescript-eslint/typescript-eslint/actions/runs/3490803456/jobs/5842786077

             91 |     // Received = Babel, Expected = TSESTree
           > 92 |     expect(babelAst).toEqual(tsestreeAst);

It'd be helpful to have the system of fixtures and snapshots documented. In particular I'd like to document what to do when these discrepencies show up in a package bump or AST fix.

#5885 is another example of where the docs would be helpful.

Edit: some context here too: #5717 (review), #5926 (comment)

Affected URL(s)

https://typescript-eslint.io/docs/maintenance/package-updates, maybe?

[bradzacher]

ideally we should be pushing to move all of our fixture tests to ast-spec where all of this stuff is handled and reported automatically.

In a future state we would have all of the fixtures moved and then an upgrade should just be like:

$ yarn add -DW @babel/core @babel/parser @babel/eslint-parser
$ (cd packages/ast-spec && yarn test -u)
$ git commit -a -m "chore: bump babel dependency"

[JoshuaKGoldberg]

@bradzacher do you think it's reasonable to file a new issue to track those migrations? If so, is there a reasonable set of upgrade instructions/steps that can be put in it?

[bradzacher]

Raised #6065

[JoshuaKGoldberg]

Marking as blocked on #6065 so we don't spend time documenting the old flow.