Closure provided by data provider is bound to different object at test time

[Bilge]

Q	A
PHPUnit version	6.5.8
PHP version	7.1.6
Installation Method	Composer

    private $foo;

    protected function setUp(): void
    {
        $this->foo = new \Exception('foo');
    }

    /**
     * @dataProvider provideClosure
     */
    public function test(\Closure $closure): void
    {
        $closure();
    }

    public function provideClosure(): \Generator
    {
        yield [function () { return $this->foo->getMessage(); }];
    }

Error : Call to a member function getMessage() on null

This doesn't work because whatever the Closure is bound to at test setup time (when provideClosure() is invoked) is not the same object as when test() is invoked. The only way around this is to rebind the closure when it is invoked, i.e. do the following:

    /**
     * @dataProvider provideClosure
     */
    public function test(\Closure $closure): void
    {
        // Workaround: rebind closure to this test instance.
        \Closure::bind($closure, $this)();
    }

If possible, closures created by data providers should be bound to the same test instance as the test class they were created by, to avoid betraying user's expectations and having to employ this ugly workaround.

[sebastianbergmann]

This is, I am afraid, expected behavior for now and you need that workaround.

All data providers are executed before the first test is run. Hopefully, eventually this will change. This is what #10 is about.