public function is_file()
{
$this->assertFalse(is_file($this->fooURL));
$this->assertFalse(is_file($this->barURL));
$this->assertTrue(is_file($this->baz1URL));
$this->assertTrue(is_file($this->baz2URL));
$this->assertFalse(is_file($this->fooURL . '/another'));
$this->assertFalse(is_file(vfsStream::url('another')));
}