getObjectForTrait() does not work for traits that declare a constructor

[oumarkonate]

Q	A
PHPUnit version	PHPUnit 6.5.14
PHP version	PHP 7.3.5
Installation Method	Composer

I test the following trait:

trait MyTrait
{
    /**
     * @var UrlInterface
     */
    private $url;

    /**
     * @param UrlInterface $url
     */
    public function __construct(UrlInterface $url)
    {
        $this->url = $url;
    }

    /**
     * @return string
     */
    public function method1(): string
    {
        return '';
    }

    /**
     * @return string
     */
    public function method2(): string
    {
        return $this->url->generate($this->otherObject);
    }
}

The test class is :

class MyTraitTest extends \PHPUnit\Framework\TestCase
{
    protected $myTrait;

    protected $url;

    public function setUp()
    {
        $this->url = $this->createMock(UrlInterface::class);

        $this->myTrait = $this->getObjectForTrait(myTrait::class, [$this->url]);
    }

    /**
     * Test method method1.
     */
    public function testMethod1()
    {
        $this->assertEmpty($this->myTrait->method1());
    }

    /**
     * Test method method2.
     */
    public function testMethod2()
    {
        $this->url->expects($this->once())
            ->method('generate')
            ->willReturn('some-string');

        $this->assertEquals('some-string', $this->myTrait->method2());
    }
}

The console output when I launch the test:

1. MyTraitTest::testMethod2
   Error: Call to a member function generate() on null

After analysis, I found variable $arguments is not used in method getObjectForTrait().

I know it's not a good practice to put the constructor in trait ... but PHP does not forbid it.

Can you fix that please?

[oumarkonate]

@sebastianbergmann Thanks for the fix.