chore: add test for fastify-plugin usage

[SimenB]

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

I tried using FastifyPluginAsyncTypebox and ran into issues with fastify-plugin. This PR is (for now at least) just a failing test.

/cc @sinclairzx81

[sinclairzx81]

@SimenB Hi! Just had a quick look at this. I think the issue likely resides inside fastify-plugin package where the fp function signature doesn't seem to support varying generic plugin arguments. The current definitions for the fp library are linked below.

https://github.com/fastify/fastify-plugin/blob/master/plugin.d.ts#L3-L17

I'm able to resolve the issue by making the following edits to the above code. (note: these edits where made directly to the plugin.d.ts definition file located inside node_modules on this branch)

Code Modifications

import {
  FastifyPluginAsync,
  FastifyPluginCallback,
  FastifyPluginOptions,
  RawServerDefault,
  FastifyTypeProviderDefault
} from 'fastify'

// ---------------------------------------------------------------------------------
// Utility Types
// ---------------------------------------------------------------------------------

export type ExtractFastifyPluginAsyncParams<T> = T extends FastifyPluginAsync<
  infer Options,
  infer Server,
  infer TypeProvider
> ? {
  Options: Options,
  Server: Server,
  TypeProvider: TypeProvider
} : {
  Options: FastifyPluginOptions,
  Server: RawServerDefault,
  TypeProvider: FastifyTypeProviderDefault,
}

export type ExtractFastifyPluginCallbackParams<T> = T extends FastifyPluginCallback<
  infer Options,
  infer Server,
  infer TypeProvider
> ? {
  Options: Options,
  Server: Server,
  TypeProvider: TypeProvider
} : {
  Options: FastifyPluginOptions,
  Server: RawServerDefault,
  TypeProvider: FastifyTypeProviderDefault,
}

/**
 * This function does three things for you:
 *   1. Add the `skip-override` hidden property
 *   2. Check bare-minimum version of Fastify
 *   3. Pass some custom metadata of the plugin to Fastify
 * @param fn Fastify plugin function
 * @param options Optional plugin options
 */
export default function fp<Plugin, Params extends ExtractFastifyPluginAsyncParams<Plugin>>(fn: Plugin, options?: PluginMetadata): FastifyPluginAsync<Params['Options'], Params['Server'], Params['TypeProvider']>;
export default function fp<Plugin, Params extends ExtractFastifyPluginAsyncParams<Plugin>>(fn: Plugin, options?: string): FastifyPluginAsync<Params['Options'], Params['Server'], Params['TypeProvider']>;
export default function fp<Plugin, Params extends ExtractFastifyPluginCallbackParams<Plugin>>(fn: Plugin, options?: PluginMetadata):  FastifyPluginCallback<Params['Options'], Params['Server'], Params['TypeProvider']>;
export default function fp<Plugin, Params extends ExtractFastifyPluginCallbackParams<Plugin>>(fn: Plugin, options?: string): FastifyPluginCallback<Params['Options'], Params['Server'], Params['TypeProvider']>;

So, the above is a quick draft that should in theory work, but needs review from the Fastify team for overall correctness. Note, I'm not too familiar with the fastify-plugin package, but maybe the above can serve as a starting point to help get things resolved.

@RafaelGSS Any thoughts on updating the fastify-plugin package to support varying generics on these plugins? Maybe there's a better way to express these definitions?

Hope this helps!
S

[sinclairzx81]

fastify/fastify-plugin#191

[RafaelGSS]

@sinclairzx81 / @SimenB could you confirm if the patch fastify/fastify-plugin#192 fixes this issue?

[sinclairzx81]

@RafaelGSS Heya. Can confirm the updates on fastify/fastify-plugin#192 do enable the TS tests on this branch to complete successfully.

[SimenB]

Sweet! Good timing with that PR 😀