不允许在函数外部的变量中使用表达式 - Expression is not allowed in a variable outside of a function

Expression is not allowed in a variable outside of a function

我想将目录链接到$screenshotPath字符串，但 PHPStorm 中出现了一个错误：不允许将表达式作为字段默认值。我该如何解决它？法典：

use PHPUnit'Extensions'SeleniumTestCase;
use ApplicationTest'Bootstrap;
class AdminLoginLogoutTest extends PHPUnit_Extensions_SeleniumTestCase {
    protected $captureScreenshotOnFailure = true;
    //$screenshotPath is giving me this error...
    protected $screenshotPath = __DIR__ . "/FailedTestsScreenshots";
    protected $screenshotUrl = "http://icho/screenshots";
    protected $path = "http://icho";
    protected function SetUp() {
        $this->setBrowser( "*firefox" );
        $this->SetBrowserUrl( $this->path );
    }
    public function testAdminLoginLogout() {
        $this->open( "/admin" );
        $this->type( "name=username", "test" );
        $this->type( "name=password", "test" );
        $this->click( "id=submitbutton" );
        $this->waitForPageToLoad( "30000" );
        $this->assertEquals( "Dashboard", $this->getText( "link=Dashboard" ) );
        $this->assertEquals( "Haios", $this->getText( "link=Haios" ) );
        $this->assertEquals( "POs", $this->getText( "link=POs" ) );
        $this->assertEquals( "Staco's", $this->getText( "link=Staco's" ) );
        $this->assertEquals( "Mail templates", $this->getText( "link=Mail templates" ) );
        $this->assertEquals( "Mailings", $this->getText( "link=Mailings" ) );
        $this->assertEquals( "Sytem texts", $this->getText( "link=System texts" ) );
        $this->assertEquals( "Advanced admin", $this->getText( "link=Advanced admin" ) );
        $this->click( "css=a[title='Sign Out']" );
        $this->click( "id=bot2-Msg1" );
        $this->waitForPageToLoad( "30000" );
        $this->assertEquals( "Login is vereist", $this->getText( "css=h2" ) );
    }
}

将其移动到构造函数（或任何其他函数）中 - 您似乎没有任何该类的构造函数，但无论如何都会调用__construct：

protected $screenshotPath = '';
public function __construct() {
    $this->$screenshotPath = __DIR__ . "/FailedTestsScreenshots";
}

或进入SetUp()：

protected function SetUp() {
    $this->$screenshotPath = __DIR__ . "/FailedTestsScreenshots";
    $this->setBrowser( "*firefox" );
    $this->SetBrowserUrl( $this->path );
}