Fix silent hang when returning cached response with FormData body from beforeRequest hook

Fixes #2232

Author: sindresorhus

source/core/index.ts

@@ -1280,7 +1280,9 @@ export default class Request extends Duplex implements RequestEvents<Request> {
 
 	private _writeRequest(chunk: any, encoding: BufferEncoding | undefined, callback: (error?: Error | null) => void): void { // eslint-disable-line @typescript-eslint/ban-types
 		if (!this._request || this._request.destroyed) {
-			// Probably the `ClientRequest` instance will throw
+			// When there's no request (e.g., using cached response from beforeRequest hook),
+			// we still need to call the callback to allow the stream to finish properly.
+			callback();
 			return;
 		}
 

test/hooks.ts

@@ -390,6 +390,29 @@ test('returning HTTP response from a beforeRequest hook', withServer, async (t,
 	t.is(body, 'Hi!');
 });
 
+test('returning HTTP response from a beforeRequest hook with FormData body', withServer, async (t, server, got) => {
+	server.post('/', echoBody);
+
+	const form = new FormData();
+	form.append('field', 'value');
+
+	const data = await got.post({
+		body: form,
+		hooks: {
+			beforeRequest: [
+				() => new Responselike({
+					statusCode: 200,
+					headers: {},
+					body: Buffer.from('{"cached": "response"}'),
+					url: '',
+				}),
+			],
+		},
+	}).json<{cached: string}>();
+
+	t.is(data.cached, 'response');
+});
+
 test('beforeRedirect is called with options and response', withServer, async (t, server, got) => {
 	server.get('/', echoHeaders);
 	server.get('/redirect', redirectEndpoint);