| name | test-typescript-errors |
| description | Verify that the TypeScript Web Playground catches and displays compiler diagnostics for invalid TypeScript. Use when testing browser-side compilation, Monaco editor integration, Run-button behavior, diagnostic formatting, or regressions where TypeScript errors may be missing from the playground Console. |
Test TypeScript Errors
Test through the browser UI with Playwright CLI. Do not infer success from Monaco squiggles or from the compiler implementation alone: enter invalid code, click Run, and inspect the rendered .compiler-error output.
Run the standard check
From the repository root, run:
.agents/skills/test-typescript-errors/scripts/verify-typescript-error.sh
The helper starts the Vite client and loads the real empty playground exercise from:
https://raw.githubusercontent.com/rstropek/ts-web-playground/refs/heads/main/exercises/emptyPlayground.yaml
It then enters:
let myVar: number = "42";
It passes only when the app renders a diagnostic containing:
Type 'string' is not assignable to type 'number'.
This deliberately exercises the app's normal exercise-loading path and requires network access to raw.githubusercontent.com. The helper closes its browser session and dev server when it exits.
Test another diagnostic
Pass the source as the first argument and an expected diagnostic substring as the second:
.agents/skills/test-typescript-errors/scripts/verify-typescript-error.sh \
'const count: number = true;' \
"Type 'boolean' is not assignable to type 'number'."
Set PLAYGROUND_URL to reuse an already-running client instead of starting Vite:
PLAYGROUND_URL=http://127.0.0.1:5173/playground/ \
.agents/skills/test-typescript-errors/scripts/verify-typescript-error.sh
Set TS_PLAYGROUND_PORT to change the helper-managed Vite port.
Interpret the result
- Treat exit code
0 and the printed PASS diagnostic as success.
- Treat a missing or mismatched diagnostic as failure, even if JavaScript was emitted or the result iframe loaded. This playground reports diagnostics without blocking emit.
- Report the entered source and the actual rendered diagnostic when handing off results.
- If the helper cannot start, first check that
client/node_modules exists, playwright-cli is installed, and the raw GitHub exercise URL is reachable. Obtain approval before installing missing dependencies.
