fix accept and content-length headers overriding

index.js

@@ -231,8 +231,8 @@ function normalizeArguments(url, opts) {
 		delete opts.query;
 	}
 
-	if (opts.json) {
-		opts.headers.accept = opts.headers.accept || 'application/json';
+	if (opts.json && opts.headers.accept === undefined) {
+		opts.headers.accept = 'application/json';
 	}
 
 	var body = opts.body;
@@ -249,7 +249,7 @@ function normalizeArguments(url, opts) {
 			body = opts.body = querystring.stringify(body);
 		}
 
-		if (!opts.headers['content-length'] && !opts.headers['transfer-encoding'] && !isStream.readable(body)) {
+		if (opts.headers['content-length'] === undefined && opts.headers['transfer-encoding'] === undefined && !isStream.readable(body)) {
 			var length = typeof body === 'string' ? Buffer.byteLength(body) : body.length;
 			opts.headers['content-length'] = length;
 		}

test/headers.js

@@ -8,6 +8,7 @@ test.before('setup', async t => {
 	s = await createServer();
 
 	s.on('/', (req, res) => {
+		req.resume();
 		res.end(JSON.stringify(req.headers));
 	});
 
@@ -25,8 +26,11 @@ test('accept-encoding', async t => {
 });
 
 test('accept header with json option', async t => {
-	const headers = (await got(s.url, {json: true})).body;
+	let headers = (await got(s.url, {json: true})).body;
 	t.is(headers.accept, 'application/json');
+
+	headers = (await got(s.url, {headers: {'accept': ''}, json: true})).body;
+	t.is(headers.accept, '');
 });
 
 test('host', async t => {
@@ -39,6 +43,11 @@ test('transform names to lowercase', async t => {
 	t.is(headers['user-agent'], 'test');
 });
 
+test('zero content-length', async t => {
+	const headers = (await got(s.url, {headers: {'content-length': 0}, body: 'sup', json: true})).body;
+	t.is(headers['content-length'], '0');
+});
+
 test.after('cleanup', async t => {
 	await s.close();
 });