Add test script for bypassing backend authentication issue

.github/workflows/js.yml

@@ -75,6 +75,7 @@ jobs:
           --mode=diff-normal
           --handler=pg
           --postgresql-url='postgres://username@127.0.0.1:5432/ferretdb'
+          --test-enable-new-auth=true
           2> ferretdb.log &
 
       - name: Run testjs for MongoDB

build/legacy-mongo-shell/test.js

@@ -1,7 +1,50 @@
+/* eslint-disable max-len */
 // Please do not merge changes in this file.
 
 (function() {
   'use strict';
 
+  let client = db.runCommand({whatsmyuri: 1}).you;
+
+  print('connected to: ' + client);
+
+  const t = db.foo;
+  t.drop();
+
+  const admin = db.getSiblingDB('admin');
+
+  let res = db.runCommand({ping: 1});
+  assert.eq(res.ok, 1, 'ping failed');
+
+  res = t.insert({});
+  assert.writeOK(res, 'insert failed');
+
+  let port = 27017;
+
+  const roles = [];
+
+  if (admin.runCommand({getParameter: '*'}).wiredTigerConcurrentReadTransactions !== undefined) {
+    roles.push({role: 'read', db: 'admin'});
+    port = 47017;
+  };
+
+
+  admin.system.users.remove({user: 'user'});
+  admin.createUser({user: 'user', pwd: '1234', roles: roles});
+
+  const mongoClient = function(uri) {
+    return new Mongo(uri);
+  };
+
+  const uri = 'mongodb://user:1234@host.docker.internal:' + port + '/?authMechanism=SCRAM-SHA-1';
+
+  try {
+    client = mongoClient(uri);
+  } catch (e) {
+    throw new Error('test.js failed: ' + e);
+  }
+
+  print('connected to: ' + client.getDB('test').runCommand({whatsmyuri: 1}).you);
+
   print('test.js passed!');
 })();