reply.code().send() does not infer correct type #4883
Description
Prerequisites
- I have written a descriptive issue title
- I have searched existing issues to ensure the regression has not already been reported
Last working version
4.18.0
Stopped working in version
4.19.0
Node.js version
18.16.0
Operating system
macOS
Operating system version (i.e. 20.04, 11.3, 10)
13.2.1
💥 Regression Report
Upgrading from 4.18.0 to 4.19.x reply.code().send() can no longer infer the correct type if the provided type is an Array<T>. Seems to do with this commit: 7d02f76.
type ReplyTypeConstrainer<RouteGenericReply, Code extends ReplyKeysToCodes<keyof RouteGenericReply>, ReplyKey = CodeToReplyKey<Code>> =
Code extends keyof RouteGenericReply ? RouteGenericReply[Code] :
[ReplyKey] extends [never] ? unknown :
ReplyKey extends keyof RouteGenericReply ? RouteGenericReply[ReplyKey] :
unknown;
type TestReplyType = ReplyTypeConstrainer<string[], 200>; // TestReplyType is a string because it fulfils the first condition of ReplyTypeConstrainer
Is the intended behaviour to force users to implement the reply type as { [code: number]: any }, or are users still allowed to provide any type as a reply?
Steps to Reproduce
import fastify from '../fastify'
const server = fastify()
type TestResponse = string[];
server.get<{ Reply: TestResponse }>(
'/ping',
{ schema: {} },
async (request, reply) => {
reply.code(200).send(['']) // type error
}
)
server.listen({ port: 8080 }, (err, address) => {
if (err) {
console.error(err)
process.exit(1)
}
console.log(`Server listening at ${address}`)
})
Expected Behavior
The correct type should be inferred, or strict even more the reply type to be a Record<HttpStatusCode, unknown>.