在codeception中加载params.php文件无效

codeception.yml的内容

class_name: ApiTester
modules:
  enabled:
    - REST:
        depends: PhpBrowser
        url : http://localhost
        part: Json

params:
    - params.php

我的php文件是：

<?php

return [
   "param1" => "some value",
   "param2" => "second value",
];

上述行的输出：

(
    [bootstrap] => 
    [coverage] => Array
        (
        )

    [params] => Array
        (
        )

    [gherkin] => Array
        (
        )
)

(
    [bootstrap] => 
    [coverage] => Array
        (
        )

    [params] => Array
        (
        )

    [gherkin] => Array
        (
        )
)