fix: Allow “undefined“ as value in headers

docs/api/Dispatcher.md

@@ -74,7 +74,7 @@ Returns: `void | Promise<ConnectData>` - Only returns a `Promise` if no `callbac
 #### Parameter: `ConnectData`
 
 * **statusCode** `number`
-* **headers** `Record<string, string | string[]>`
+* **headers** `Record<string, string | string[] | undefined>`
 * **socket** `stream.Duplex`
 * **opaque** `unknown`
 
@@ -383,7 +383,7 @@ Extends: [`RequestOptions`](#parameter-requestoptions)
 #### Parameter: PipelineHandlerData
 
 * **statusCode** `number`
-* **headers** `Record<string, string | string[]>`
+* **headers** `Record<string, string | string[] | undefined>`
 * **opaque** `unknown`
 * **body** `stream.Readable`
 * **context** `object`
@@ -644,7 +644,7 @@ Returns: `void | Promise<StreamData>` - Only returns a `Promise` if no `callback
 #### Parameter: `StreamFactoryData`
 
 * **statusCode** `number`
-* **headers** `Record<string, string | string[]>`
+* **headers** `Record<string, string | string[] | undefined>`
 * **opaque** `unknown`
 * **onInfo** `({statusCode: number, headers: Record<string, string | string[]>}) => void | null` (optional) - Default: `null` - Callback collecting all the info headers (HTTP 100-199) received.
 
@@ -853,9 +853,9 @@ Emitted when dispatcher is no longer busy.
 
 ## Parameter: `UndiciHeaders`
 
-* `Record<string, string | string[]> | string[] | null`
+* `Record<string, string | string[] | undefined> | string[] | null`
 
-Header arguments such as `options.headers` in [`Client.dispatch`](Client.md#clientdispatchoptions-handlers) can be specified in two forms; either as an object specified by the `Record<string, string | string[]>` (`IncomingHttpHeaders`) type, or an array of strings. An array representation of a header list must have an even length or an `InvalidArgumentError` will be thrown.
+Header arguments such as `options.headers` in [`Client.dispatch`](Client.md#clientdispatchoptions-handlers) can be specified in two forms; either as an object specified by the `Record<string, string | string[] | undefined>` (`IncomingHttpHeaders`) type, or an array of strings. An array representation of a header list must have an even length or an `InvalidArgumentError` will be thrown.
 
 Keys are lowercase and values are not modified.
 

package.json

@@ -98,7 +98,7 @@
     "table": "^6.8.0",
     "tap": "^16.1.0",
     "tsd": "^0.25.0",
-    "typescript": "^4.8.4",
+    "typescript": "^4.9.5",
     "wait-on": "^6.0.0",
     "ws": "^8.11.0"
   },

test/types/dispatcher.test-d.ts

@@ -1,3 +1,4 @@
+import { IncomingHttpHeaders } from 'http'
 import { Duplex, Readable, Writable } from 'stream'
 import { expectAssignable, expectType } from 'tsd'
 import { Dispatcher } from '../..'
@@ -9,11 +10,18 @@ expectAssignable<Dispatcher>(new Dispatcher())
 {
   const dispatcher = new Dispatcher()
 
+  const nodeCoreHeaders = {
+    authorization: undefined,
+    ['content-type']: 'application/json'
+  } satisfies IncomingHttpHeaders;
+
   // dispatch
   expectAssignable<boolean>(dispatcher.dispatch({ path: '', method: 'GET' }, {}))
   expectAssignable<boolean>(dispatcher.dispatch({ origin: '', path: '', method: 'GET' }, {}))
+  expectAssignable<boolean>(dispatcher.dispatch({ origin: '', path: '', method: 'GET', headers: { authorization: undefined } }, {}))
   expectAssignable<boolean>(dispatcher.dispatch({ origin: '', path: '', method: 'GET', headers: [] }, {}))
   expectAssignable<boolean>(dispatcher.dispatch({ origin: '', path: '', method: 'GET', headers: {} }, {}))
+  expectAssignable<boolean>(dispatcher.dispatch({ origin: '', path: '', method: 'GET', headers: nodeCoreHeaders }, {}))
   expectAssignable<boolean>(dispatcher.dispatch({ origin: '', path: '', method: 'GET', headers: null, reset: true }, {}))
   expectAssignable<boolean>(dispatcher.dispatch({ origin: new URL('http://localhost'), path: '', method: 'GET' }, {}))
 

test/types/header.test-d.ts

@@ -0,0 +1,16 @@
+import { IncomingHttpHeaders as CoreIncomingHttpHeaders } from "http";
+import { expectAssignable, expectNotAssignable } from "tsd";
+import { IncomingHttpHeaders } from "../../types/header";
+
+const headers = {
+  authorization: undefined,
+  ["content-type"]: "application/json",
+} satisfies CoreIncomingHttpHeaders;
+
+expectAssignable<IncomingHttpHeaders>(headers);
+
+// It is why we do not need to add ` | null` to `IncomingHttpHeaders`:
+expectNotAssignable<CoreIncomingHttpHeaders>({
+  authorization: null,
+  ["content-type"]: "application/json",
+});

types/header.d.ts

@@ -1,4 +1,4 @@
 /**
  * The header type declaration of `undici`.
  */
-export type IncomingHttpHeaders = Record<string, string | string[]>;
+export type IncomingHttpHeaders = Record<string, string | string[] | undefined>;