Fix content-length header not being set when using custom content-type

Fixes #996

Author: szmarczak

source/normalize-arguments.ts

@@ -377,7 +377,7 @@ export const normalizeRequestArguments = async (options: NormalizedOptions): Pro
 	// Content-Length header field when the request message does not contain
 	// a payload body and the method semantics do not anticipate such a
 	// body.
-	if (noContentType && is.undefined(headers['transfer-encoding'])) {
+	if (is.undefined(headers['content-length']) && is.undefined(headers['transfer-encoding'])) {
 		if (
 			(options.method === 'POST' || options.method === 'PUT' || options.method === 'PATCH') &&
 			!is.undefined(uploadBodySize)

test/post.ts

@@ -113,6 +113,22 @@ test('`content-length` header with string body', withServer, async (t, server, g
 	t.is(headers['content-length'], '3');
 });
 
+test('`content-length` header with json body', withServer, async (t, server, got) => {
+	server.post('/', echoHeaders);
+
+	const {body} = await got.post({json: {foo: 'bar'}});
+	const headers = JSON.parse(body);
+	t.is(headers['content-length'], '13');
+});
+
+test('`content-length` header with form body', withServer, async (t, server, got) => {
+	server.post('/', echoHeaders);
+
+	const {body} = await got.post({form: {foo: 'bar'}});
+	const headers = JSON.parse(body);
+	t.is(headers['content-length'], '7');
+});
+
 test('`content-length` header with Buffer body', withServer, async (t, server, got) => {
 	server.post('/', echoHeaders);
 
@@ -143,6 +159,19 @@ test('`content-length` header is not overriden', withServer, async (t, server, g
 	t.is(headers['content-length'], '10');
 });
 
+test('`content-length` header is present when using custom content-type', withServer, async (t, server, got) => {
+	server.post('/', echoHeaders);
+
+	const {body} = await got.post({
+		json: {foo: 'bar'},
+		headers: {
+			'content-type': 'custom'
+		}
+	});
+	const headers = JSON.parse(body);
+	t.is(headers['content-length'], '13');
+});
+
 test('`content-length` header disabled for chunked transfer-encoding', withServer, async (t, server, got) => {
 	server.post('/', echoHeaders);