Add unittest to validate TypeScript types

[saschanaz]

For example, BrowserNames is now gone but the schema still refers to it, causing build failure:

browser-compat-data/schemas/compat-data.schema.json

Line 184 in 2888cf5

"tsType": "Partial<Record<BrowserNames, SupportStatement>>"

There are also several occurrences of import('../../types').Identifier in linters which are now all broken:

browser-compat-data/test/linter/test-status.js

Line 7 in 420c23b

* @typedef {import('../../types').Identifier} Identifier

[saschanaz]

https://github.com/mdn/browser-compat-data/releases/tag/v5.0.2

This release includes a fundamental change to the TypeScript definitions.

That sounds like a breaking change 🤔, there should be some deprecated typedefs until 6.x.

[queengooborg]

TypeScript definitions were not covered by semantic versioning during this release. However, going forward, they will be (especially since they're auto-generated). I've just opened up a fix for the typo, and all of those linter typedef imports will be fixed in #16333.

[saschanaz]

That's not all. Please reopen and add tests before closing this.

node_modules/@mdn/browser-compat-data/types.d.ts:134:44 - error TS2344: Type 'Omit<string, "__compat">' does not satisfy the constraint 'string | number | symbol'.

134 export interface Identifier extends Record<Omit<string, '__compat'>, Identifier> {
                                               ~~~~~~~~~~~~~~~~~~~~~~~~

node_modules/@mdn/browser-compat-data/types.d.ts:255:3 - error TS2411: Property '__compat' of type 'CompatStatement | undefined' is not assignable to 'string' index type 'Identifier'.

255   __compat?: CompatStatement;

[queengooborg]

I closed this issue because any remaining TypeScript definition issues will be resolved in #16333, when BCD's internals are migrated to TypeScript and depend on these types. I plan to release an update to BCD later this week to deploy TypeScript fixes.

[queengooborg]

Ah, wait: I now see this is talking about writing a unittest. Apologies, I thought this was just about the invalid TypeScript definition.

For the unittest, if you're down to write a PR to add one (and fix up any issues in separate PRs), I'd be happy to review and merge it.