fix(types): cannot .use non-return mw from createMiddleware (#4465)

* fix(types): cannot `.use` non-return mw from `createMiddleware`

* chore: add tests

Author: NamesMT

src/helper/factory/index.test.ts

@@ -3,7 +3,7 @@ import { expectTypeOf } from 'vitest'
 import { hc } from '../../client'
 import type { ClientRequest } from '../../client/types'
 import { Hono } from '../../index'
-import type { ExtractSchema, ToSchema, TypedResponse } from '../../types'
+import type { Env, ExtractSchema, MiddlewareHandler, ToSchema, TypedResponse } from '../../types'
 import type { ContentfulStatusCode } from '../../utils/http-status'
 import type { Equal, Expect } from '../../utils/types'
 import { validator } from '../../validator'
@@ -63,6 +63,14 @@ describe('createMiddleware', () => {
       }
     )
   })
+
+  it('Should default to MiddlewareHandler<E, P, I, Response>', async () => {
+    const middleware = createMiddleware(async (c, next) => {
+      await next()
+    })
+    type Expected = MiddlewareHandler<any, string, {}, Response>
+    type _verify = Expect<Equal<Expected, typeof middleware>>
+  })
 })
 
 describe('createHandler', () => {
@@ -366,6 +374,16 @@ describe('createFactory', () => {
       }
       type verify = Expect<Equal<Expected, Actual>>
     })
+
+    it('Should default to MiddlewareHandler<E, P, I, Response>', async () => {
+      const factory = createFactory()
+
+      const middleware = factory.createMiddleware(async (c, next) => {
+        await next()
+      })
+      type Expected = MiddlewareHandler<Env, string, {}, Response>
+      type _verify = Expect<Equal<Expected, typeof middleware>>
+    })
   })
 
   it('Should use the default app options', async () => {

src/helper/factory/index.ts

@@ -305,9 +305,9 @@ export class Factory<E extends Env = Env, P extends string = string> {
     return app
   }
 
-  createMiddleware = <I extends Input = {}, R extends HandlerResponse<any> = Response>(
-    middleware: MiddlewareHandler<E, P, I, R>
-  ): MiddlewareHandler<E, P, I, R> => middleware
+  createMiddleware = <I extends Input = {}, R extends HandlerResponse<any> | void = void>(
+    middleware: MiddlewareHandler<E, P, I, R extends void ? Response : R>
+  ): MiddlewareHandler<E, P, I, R extends void ? Response : R> => middleware
 
   createHandlers: CreateHandlersInterface<E, P> = (...handlers: any) => {
     // @ts-expect-error this should not be typed
@@ -324,7 +324,7 @@ export const createMiddleware = <
   E extends Env = any,
   P extends string = string,
   I extends Input = {},
-  R extends HandlerResponse<any> = Response
+  R extends HandlerResponse<any> | void = void
 >(
-  middleware: MiddlewareHandler<E, P, I, R>
-): MiddlewareHandler<E, P, I, R> => middleware
+  middleware: MiddlewareHandler<E, P, I, R extends void ? Response : R>
+): MiddlewareHandler<E, P, I, R extends void ? Response : R> => middleware