Add automatic keep-alive header when shouldKeepAlive is true

src/js/node/_http_server.ts

@@ -1550,6 +1550,12 @@ function _writeHead(statusCode, reason, obj, response) {
     }
   }
 
+  // Automatically add Connection: keep-alive header if shouldKeepAlive is true
+  // and no Connection header has been set
+  if (response.shouldKeepAlive && !response.hasHeader("connection")) {
+    response.setHeader("Connection", "keep-alive");
+  }
+
   updateHasBody(response, statusCode);
 }
 

test/js/node/test/parallel/test-http-automatic-headers.js

@@ -0,0 +1,30 @@
+const common = require('../common');
+const assert = require('assert');
+const http = require('http');
+
+const server = http.createServer(common.mustCall((req, res) => {
+  res.setHeader('X-Date', 'foo');
+  res.setHeader('X-Connection', 'bar');
+  res.setHeader('X-Content-Length', 'baz');
+  res.end();
+}));
+server.listen(0);
+
+server.on('listening', common.mustCall(() => {
+  const agent = new http.Agent({ port: server.address().port, maxSockets: 1 });
+  http.get({
+    port: server.address().port,
+    path: '/hello',
+    agent: agent
+  }, common.mustCall((res) => {
+    assert.strictEqual(res.statusCode, 200);
+    assert.strictEqual(res.headers['x-date'], 'foo');
+    assert.strictEqual(res.headers['x-connection'], 'bar');
+    assert.strictEqual(res.headers['x-content-length'], 'baz');
+    assert(res.headers.date);
+    assert.strictEqual(res.headers.connection, 'keep-alive');
+    assert.strictEqual(res.headers['content-length'], '0');
+    server.close();
+    agent.destroy();
+  }));
+}));