test: check endless loop while writing empty string

Refs: #18673
PR-URL: #18924
Refs: #18673
Refs: https://github.com/nodejs/node/blob/v9.5.0/src/node_http2.cc#L1481-L1484
Refs: https://github.com/nodejs/node/blob/v9.5.0/lib/_http_outgoing.js#L659-L661
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: XadillaX

test/parallel/test-http2-client-write-empty-string.js

@@ -0,0 +1,54 @@
+'use strict';
+
+constassert=require('assert');
+consthttp2=require('http2');
+
+constcommon=require('../common');
+if(!common.hasCrypto)
+common.skip('missing crypto');
+
+for(constchunkSequenceof[
+[''],
+['','']
+]){
+constserver=http2.createServer();
+server.on('stream',common.mustCall((stream,headers,flags)=>{
+stream.respond({'content-type': 'text/html'});
+
+letdata='';
+stream.on('data',common.mustNotCall((chunk)=>{
+data+=chunk.toString();
+}));
+stream.on('end',common.mustCall(()=>{
+stream.end(`"${data}"`);
+}));
+}));
+
+server.listen(0,common.mustCall(()=>{
+constport=server.address().port;
+constclient=http2.connect(`http://localhost:${port}`);
+
+constreq=client.request({
+':method': 'POST',
+':path': '/'
+});
+
+req.on('response',common.mustCall((headers)=>{
+assert.strictEqual(headers[':status'],200);
+assert.strictEqual(headers['content-type'],'text/html');
+}));
+
+letdata='';
+req.setEncoding('utf8');
+req.on('data',common.mustCallAtLeast((d)=>data+=d));
+req.on('end',common.mustCall(()=>{
+assert.strictEqual(data,'""');
+server.close();
+client.close();
+}));
+
+for(constchunkofchunkSequence)
+req.write(chunk);
+req.end();
+}));
+}