tests: add change user before connect test

test/unit/connection/test-change-user-before-connect.js

@@ -0,0 +1,25 @@
+var assert     = require('assert');
+var common     = require('../../common');
+var connection = common.createConnection({
+  port : common.fakeServerPort,
+  user : 'user_1'
+});
+
+var server = common.createFakeServer();
+
+server.listen(common.fakeServerPort, function(err) {
+  assert.ifError(err);
+  assert.equal(connection.state, 'disconnected');
+
+  connection.changeUser({user: 'user_2'}, function (err) {
+    assert.ifError(err);
+
+    connection.query('SELECT CURRENT_USER()', function (err, result) {
+      assert.ifError(err);
+      assert.strictEqual(result[0]['CURRENT_USER()'], 'user_2@localhost');
+
+      connection.destroy();
+      server.destroy();
+    });
+  });
+});