test: increase coverage for _http_incoming.js

Add coverage for IncomingMessage.prototype.connection setter.

PR-URL: nodejs#31093
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>

test/parallel/test-http-incoming-message-connection-setter.js

@@ -0,0 +1,18 @@
+'use strict';
+
+// Test that the setter for http.IncomingMessage,prototype.connection sets the
+// socket property too.
+require('../common');
+
+const assert = require('assert');
+const http = require('http');
+
+const incomingMessage = new http.IncomingMessage();
+
+assert.strictEqual(incomingMessage.connection, undefined);
+assert.strictEqual(incomingMessage.socket, undefined);
+
+incomingMessage.connection = 'fhqwhgads';
+
+assert.strictEqual(incomingMessage.connection, 'fhqwhgads');
+assert.strictEqual(incomingMessage.socket, 'fhqwhgads');