fix: add opt-in appendAutoPrefix for directory auto prefixes

[SergioChan]

Summary

• add a new appendAutoPrefix autoload option (default false)
• keep existing behavior by default (plugin.autoPrefix still overrides directory-derived prefixes)
• when appendAutoPrefix: true, concatenate directory prefix + plugin.autoPrefix
• add Issue autoPrefix overwrites directory path set by dirNameRoutePrefix #205 coverage to verify both default and opt-in behaviors
• document the new option and update TypeScript definitions

Issue

Closes #205 and close this PR #350

Validation

• node --test test/issues/205/test.js
• node --test test/commonjs/basic.js

[SergioChan]

Thanks for the review — I pushed an update to clarify the behavior and example in README.

What changed:

• Rewrote the appendAutoPrefix section to explicitly describe both modes (false vs true).
• Added a concrete directory example showing routes/children/new-routes.js exporting autoPrefix = '/batch'.
• Added explicit resulting route paths for both modes:
  • default: /your-parent-prefix/batch/entity
  • append mode: /your-parent-prefix/children/batch/entity

Validation:

• node --test test/issues/205/test.js

If you want, I can also add a short one-line cross-reference from dirNameRoutePrefix to appendAutoPrefix for discoverability.

[mcollina]

lgtm

[Tony133]

@SergioChan as soon as you have time, could you resolve the two issues that were flagged? The one regarding the tests is the priority, at the very least.

[SergioChan]

@Tony133 resolved both flagged threads.

• Tests: flattened the nested describe blocks into two direct it cases in 4dba83c, with each test managing its own Fastify lifecycle.
• API suggestion: replied with the rationale for keeping appendAutoPrefix as the global opt-in proposed in issue autoPrefix overwrites directory path set by dirNameRoutePrefix #205; the suggestion was non-blocking and the current behavior remains explicitly documented.

Validation:

• npm run lint
• node --test test/issues/205/test.js
• npm test (277 unit tests passed, 100% coverage)

Both review threads are now resolved.

[Tony133]

@Tony133 resolved both flagged threads.

• Tests: flattened the nested describe blocks into two direct it cases in 4dba83c, with each test managing its own Fastify lifecycle.
• API suggestion: replied with the rationale for keeping appendAutoPrefix as the global opt-in proposed in issue autoPrefix overwrites directory path set by dirNameRoutePrefix #205; the suggestion was non-blocking and the current behavior remains explicitly documented.

Validation:

• npm run lint
• node --test test/issues/205/test.js
• npm test (277 unit tests passed, 100% coverage)

Both review threads are now resolved.

Thanks!

[Tony133]

@SergioChan one last change: can you update the test so we remove the try/finally block in favor of t.after()? It keeps the test even flatter and cleaner:

'use strict'

const { describe, it } = require('node:test')
const assert = require('node:assert')
const path = require('node:path')
const Fastify = require('fastify')
const autoLoad = require('../../../')

describe('Issue 205: append autoPrefix to directory prefixes without breaking defaults', function () {
  it('should keep autoPrefix overriding directory prefixes by default', async function (t) {
    const app = Fastify()
    t.after(() => app.close())

    app.register(autoLoad, {
      dir: path.join(__dirname, 'routes'),
      options: { prefix: '/hooked-plugin' }
    })
    await app.ready()

    const overridden = await app.inject({ method: 'GET', url: '/hooked-plugin/batch/entity' })
    assert.strictEqual(overridden.statusCode, 200)
    assert.deepStrictEqual(overridden.json(), { ok: true })

    const appended = await app.inject({ method: 'GET', url: '/hooked-plugin/children/batch/entity' })
    assert.strictEqual(appended.statusCode, 404)
  })

  it('should concatenate directory prefixes before plugin autoPrefix when appendAutoPrefix is true', async function (t) {
    const app = Fastify()
    t.after(() => app.close())

    app.register(autoLoad, {
      dir: path.join(__dirname, 'routes'),
      options: { prefix: '/hooked-plugin' },
      appendAutoPrefix: true
    })
    await app.ready()

    const appended = await app.inject({ method: 'GET', url: '/hooked-plugin/children/batch/entity' })
    assert.strictEqual(appended.statusCode, 200)
    assert.deepStrictEqual(appended.json(), { ok: true })

    const overridden = await app.inject({ method: 'GET', url: '/hooked-plugin/batch/entity' })
    assert.strictEqual(overridden.statusCode, 404)
  })
})

[SergioChan]

@Tony133 addressed in 0653c09. Both tests now register Fastify cleanup with t.after(() => app.close()), and the try/finally blocks have been removed as suggested.

Validation:

• npm run lint
• node --test test/issues/205/test.js
• npm test (277 unit tests passed, 100% coverage)