UnexportedHooksError

The Cause

A hook was created but never exported, so nothing can reach it.

Hook discovery is export-based: the sampler imports each file under .thymian/sampler/hooks/ and looks at what it exports. A hook is a value, and a value nothing exports is a value nobody has.

import { beforeEach } from '@thymian/hooks';

// Creates a hook. Nothing can find it.
beforeEach('GET /launches -> 200 (application/json)', (request) => {
  request.headers['x-trace'] = 'yes';
});

This compiles, runs, and does nothing — which is why it is an error rather than a warning. A hook that never fires looks exactly like a hook that had nothing to do, so there is no run in which you would rather find out later.

What to do

Assign it to an export. The name is yours; only the export matters.

import { beforeEach } from '@thymian/hooks';

export const addTrace = beforeEach('GET /launches -> 200 (application/json)', (request) => {
  request.headers['x-trace'] = 'yes';
});

A default export works, and so does an array — useful when one file builds several hooks in a loop:

export default beforeEach(/* … */);

export const all = [beforeEach(/* … */), afterEach(/* … */)];

The error names the file that created each one:

2 sampler hooks are created but never exported, so nothing can reach them.
Try this:
  * forgot.ts: a beforeEach hook was created here but never exported,
    so nothing can reach it
  * Assign it to an export, as in: export const shape = beforeEach(...)

What this does not report

A hook in a shared module that another file re-exports is reachable, and is not reported. The file that merely imports the module without re-exporting the hook is not accused either: the hook is one object, however many files import it, and one export anywhere is enough for it to fire.

hooks/shared.ts

export const shared = beforeEach(/* … */);

// hooks/re-export.ts
export { shared } from './shared.js';

Two hooks that agree on their kind, their target and their callback source are still two hooks. An unexported one is reported even when an exported twin exists, because the twin firing does not make the unexported one reachable.