Not work if mocked in test method and tests was run from phpunit command

[KartaviK]

Example code:

class MyTest extends \PHPUnit\Framework\TestCase
{
    public function testExample(): void
    {
        $microtime = $this->getFunctionMock("My\\Namespace", 'microtime');
        $microtime->expects($this->once())
            ->willReturn('123456');
    }
}

if i try run only this test with --filter - it will pass. But if i run all tests - it will crash.
If i remove this logic to setUp method - it will pass in any case.

[KartaviK]

I understand that it is a bug that described in readme