BridgeJS: Check generated TypeScript validity in test suites

[krodak]

Should close: #593

Overview

BridgeJS generates .d.ts TypeScript declaration files, but nothing validates they are actually valid TypeScript. PR #592 fixed a bug where the function keyword was missing from namespace function declarations.

Any project running strict TypeScript type-checking (tsc --noEmit) without skipLibCheck would fail on the generated declarations (and it did 😅 ).

Approach

Add a tsc --noEmit check against all .d.ts snapshot files using the already-installed typescript (^5.8.2) from the root package.json, so no new dependencies.

• ** why an npm script rather than a Swift test?** The BridgeJS Swift tests have no precedent for shelling out to Node tools. The test-bridgejs-against-swift-versions CI job runs in containers where tool availability differs. Keeping TypeScript validation in TypeScript tooling seems like the cleanest approach, but not an expert on that, so maybe there is better way.

• why not integrated into snapshot assertions? The assertSnapshot() helper is a clean, general-purpose utility. Adding tsc coupling would slow every assertion and require handling "tsc not found" inside what should be a simple file comparison.

Usage

npm ci
npm run check:bridgejs-dts

Notes

This check immediately surfaced existing codegen bugs - issues with type definitions for PointTag, TSDirectionTag, TSThemeTag, and TSHttpStatusTag in 3 snapshot files. I'll add separate issue for that, will fix in separate PR, then rebase this one, so we'll know that this approach actually works for us 👌🏻

So failing CI for this one is actual sign it works, not a bug 😅

[MaxDesiatov]

Nice! Thank you 🤩

[kateinoigakukun]

Thanks! And glad to see it already caught an issue 😄