Add support for FormData request body

documentation/2-options.md

@@ -271,7 +271,7 @@ stream.on('data', console.log);
 
 ### `body`
 
-**Type: `string | Buffer | stream.Readable | Generator | AsyncGenerator` or [`form-data` instance](https://github.com/form-data/form-data)**
+**Type: `string | Buffer | stream.Readable | Generator | AsyncGenerator | FormData` or [`form-data` instance](https://github.com/form-data/form-data)**
 
 The payload to send.
 
@@ -290,6 +290,22 @@ console.log(data);
 //=> 'Hello, world!'
 ```
 
+Since Got 12 you can use spec-compliant FormData objects as request body, such as [`formdata-node`](https://github.com/octet-stream/form-data) or [`formdata-polyfill`](https://github.com/jimmywarting/FormData):
+
+```js
+import got from 'got';
+
+import {FormData} from 'formdata-node'; // or 'formdata-polyfill/esm.min.js'
+
+const form = new FormData();
+
+form.set('greeting', 'Hello, world!');
+
+const {data} = await got.post('https://httpbin.org/post', {
+	body: form
+});
+```
+
 #### **Note:**
 > - If `body` is specified, then the `json` or `form` option cannot be used.
 

source/core/index.ts

@@ -128,7 +128,7 @@ const proxiedRequestEvents = [
 	'upgrade',
 ] as const;
 
-const noop = () => {};
+const noop = (): void => {};
 
 type UrlType = ConstructorParameters<typeof Options>[0];
 type OptionsType = ConstructorParameters<typeof Options>[1];
@@ -572,10 +572,13 @@ export default class Request extends Duplex implements RequestEvents<Request> {
 
 			if (isBody) {
 				// Body is spec-compliant FormData
-				if (isFormDataLike(options.body) && noContentType) {
+				if (isFormDataLike(options.body)) {
 					const encoder = new FormDataEncoder(options.body);
 
-					headers['content-type'] = encoder.headers['Content-Type'];
+					if (noContentType) {
+						headers['content-type'] = encoder.headers['Content-Type'];
+					}
+
 					headers['content-length'] = encoder.headers['Content-Length'];
 
 					options.body = encoder.encode();

test/headers.ts

@@ -196,6 +196,21 @@ test('sets `content-length` header for spec-compliant FormData', withServer, asy
 	t.is(headers['content-length'], encoder.headers['Content-Length']);
 });
 
+test('manual `content-type` header should be allowed with spec-compliant FormData', withServer, async (t, server, got) => {
+	server.post('/', echoHeaders);
+
+	const form = new FormDataNode();
+	form.set('a', 'b');
+	const {body} = await got.post({
+		headers: {
+			'content-type': 'custom'
+		},
+		body: form,
+	});
+	const headers = JSON.parse(body);
+	t.is(headers['content-type'], 'custom');
+});
+
 test('stream as `options.body` does not set `content-length` header', withServer, async (t, server, got) => {
 	server.post('/', echoHeaders);