Work with void-returning async handlers

Author: trevor-leach

README.md

@@ -41,11 +41,12 @@ it.('should work', async (done) => {
 
 ## The Solution
 
-This module exports 2 utility types, `SyncHandler` and `AsyncHandler`, that transform the handlers from [@types/aws-lambda](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/aws-lambda) into the types that are intended to be implemented. It also reexports everything from [@types/aws-lambda](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/aws-lambda) for convenience.
+This module exports 2 utility types, - `SyncHandler` and `AsyncHandler` - that transform the handlers from [@types/aws-lambda](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/aws-lambda) into the types that are intended to be implemented.
 
 ### Example
 ```typescript
-import {AsyncHandler, SyncHandler, APIGatewayProxyHandler} from "aws-lambda-consumer"
+import { AsyncHandler, SyncHandler } from "aws-lambda-consumer"
+import { APIGatewayProxyHandler } from "aws-lambda"
 
 // (event: APIGatewayProxyEvent, context: Context, callback: Callback<APIGatewayProxyResult>) => void
 type SyncAPIGatewayProxyHandler  = SyncHandler<APIGatewayProxyHandler>

index.ts

@@ -9,4 +9,4 @@ export type SyncHandler<T extends Handler> = (
 export type AsyncHandler<T extends Handler> = (
 	event: Parameters<T>[0],
 	context: Parameters<T>[1],
-) => Promise<NonNullable<Parameters<Parameters<T>[2]>[1]>>;
+) => Promise<Parameters<Parameters<T>[2]>[1] extends void ? void : NonNullable<Parameters<Parameters<T>[2]>[1]>>;

package-lock.json

@@ -1,6 +1,6 @@
 {
 	"name": "aws-lambda-consumer",
-	"version": "2.0.0",
+	"version": "2.1.0",
 	"description": "Typescript types that transform the handler function types from @types/aws-lambda into the stricter synchronous and asynchronous signatures that are intended to be implemented",
 	"publishConfig": {
 		"registry": "https://registry.npmjs.org"
@@ -29,8 +29,8 @@
 		"@types/aws-lambda": "^8.10"
 	},
 	"devDependencies": {
-		"tsd": "^0.22",
-		"typescript": "^4.7.4"
+		"tsd": "^0.25",
+		"typescript": "^4.9.5"
 	},
 	"tsd": {
 		"directory": "test"

package.json

@@ -13,7 +13,11 @@ type Event  = "Event";
 type Result = "Result";
 
 let SH!: SyncHandler<Handler<Event, Result>>;
+let SHV!: SyncHandler<Handler<Event, void>>;
 let AH!: AsyncHandler<Handler<Event, Result>>;
+let AHV!: AsyncHandler<Handler<Event, void>>;
 
 expectType<(event: Event, context: Context, callback: Callback<Result>) => void>(SH);
+expectType<(event: Event, context: Context, callback: Callback<void>) => void>(SHV);
 expectType<(event: Event, context: Context) => Promise<Result>>(AH);
+expectType<(event: Event, context: Context) => Promise<void>>(AHV);