feat: tests

backend/proxy/src/port-scanner.ts

@@ -0,0 +1,22 @@
+import {createServer, Server} from 'net';
+
+/**
+ * Checks if a port is in use
+ */
+async function isPortFree(port: number, hostname?: string): Promise<boolean> {
+  return new Promise((resolve, reject) => {
+    const server: Server = createServer()
+      .once('error', error => {
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        if ((error as any).code === 'EADDRINUSE') {
+          resolve(true);
+        } else {
+          reject(error);
+        }
+      })
+      .once('listening', () => server.once('close', () => resolve(false)).close())
+      .listen(port, hostname);
+  });
+}
+
+export default {isPortFree};