How to detect fake function with PHPStan

I'm using phpstan-codeigniter and it seems to work fine, except for the `fake' function, which is not recognized wherever I use it. It says "Function fake not found".

This is my phpstan.neon:

Code:

includes:
  - vendor/codeigniter/phpstan-codeigniter/extension.neon

parameters:
  level: 6
  paths:
    - app/
    - tests/
  bootstrapFiles:
    -  vendor/codeigniter4/framework/system/Test/bootstrap.php
  excludePaths:
    - app/Views/*

How to make PHPStan detect the fake function?