tests(ast-spec): make PunctuatorTokenToText more type-safe

[MichaelDeBoey]

Follow-up of #3496

We should somehow test that all possible values of PunctuationSyntaxKind are definitely included.
If not, this should error out somehow.

I first tried doing

export const PunctuatorTokenToText: Record<PunctuationSyntaxKind, string> = {
  // ...
}

and this errored out (as expected) because SyntaxKind.BacktickToken isn't includes, but is included in PunctuationSyntaxKind.
Not including the type makes it also of type string again, which will fail #3461 & #3462.

This however made it a value instead of a type and had the implication that SyntaxKind.BarBarEqualsToken, SyntaxKind.AmpersandAmpersandEqualsToken & SyntaxKind.QuestionQuestionEqualsToken couldn't be added as they'll only be added to PunctuationSyntaxKind in TS 4.4 (they're currently included on main).

In TS 4.4 the new SyntaxKind.HashToken should also be included, so I think it would be nice to have it somehow error out if we don't include that when updating our TS version.

@bradzacher @JamesHenry Any idea how I can make this error out when some values aren't included or how I should write a test that can fail when a new value isn't included here?

[typescript-eslint]

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[MichaelDeBoey]

@bradzacher @JamesHenry Do you have any idea how I can make this error out as explained in the above message?

Would love to work on this one further, but don't see a solution right away.

[bradzacher]

can you do something similar to what I did in this?

typescript-eslint/packages/ast-spec/tests/ast-node-types.test.ts

Lines 1 to 16 in e2e76a7

	import type { AST_NODE_TYPES } from '../src/ast-node-types';
	import type { Node } from '../src/unions/Node';
	type GetKeys<T extends AST_NODE_TYPES> = keyof Extract<Node, { type: T }>;
	type AllKeys = {
	readonly [T in AST_NODE_TYPES]: GetKeys<T>;
	};
	type TakesString<T extends Record<string, string>> = T;
	// @ts-expect-error: purposely unused
	type _Test =
	// forcing the test onto a new line so it isn't covered by the expect error
	// If there are any enum members that don't have a corresponding TSESTree.Node, then this line will error with "Type 'string | number | symbol' is not assignable to type 'string'."
	TakesString<AllKeys> | void;

[codecov]

Codecov Report

Merging #3529 (e2e76a7) into master (44f9c07) will decrease coverage by 0.00%.
The diff coverage is n/a.

❗ Current head e2e76a7 differs from pull request most recent head 5ef6efb. Consider uploading reports for the commit 5ef6efb to get more accurate results

@@            Coverage Diff             @@
##           master    #3529      +/-   ##
==========================================
- Coverage   92.64%   92.63%   -0.01%     
==========================================
  Files         326      325       -1     
  Lines       11253    11236      -17     
  Branches     3171     3168       -3     
==========================================
- Hits        10425    10409      -16     
+ Misses        368      367       -1     
  Partials      460      460              

Flag	Coverage Δ
unittest	92.63% <0.00%> (-0.01%)	⬇️

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Impacted Files	Coverage Δ
...ackages/experimental-utils/src/ts-eslint/Linter.ts	100.00% <0.00%> (ø)
...ages/eslint-plugin/src/rules/prefer-regexp-exec.ts	100.00% <0.00%> (ø)
...ges/experimental-utils/src/ts-eslint/RuleTester.ts	100.00% <0.00%> (ø)
packages/eslint-plugin/src/util/escapeRegExp.ts

[MichaelDeBoey]

@bradzacher I don't see directly how I can use the mentioned test in my use-case tbh. 🤔

A bit more context (or even the test if you like) would be welcome.

[bradzacher]

 // @ts-expect-error: purposely unused
type _AllKeys = {
  // no error as all PunctuationSyntaxKind are covered
  readonly [T in PunctuationSyntaxKind]: PunctuatorTokenToText[T]; 
};


// example showing if we miss one of the PunctuationSyntaxKind

interface AccidentallyIncomplete {
  [SyntaxKind.CaretEqualsToken]: '^=';
}

// @ts-expect-error: purposely unused
type _AllKeysError = {
  readonly [T in PunctuationSyntaxKind]: AccidentallyIncomplete[T]; 
//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^ error: Type 'T' cannot be used to index type 'AccidentallyIncomplete'.
}

repl

[MichaelDeBoey]

@bradzacher The problem is, it should already error out as BacktickToken is commented out and should be included in the interface. 🤔

[bradzacher]

i forgot to delete it when I copy pasted - but delete the extends and that will fix it.

[bradzacher]

LGTM - thanks for thsi!