public function assertMissing($selector)
    {
        $fullSelector = $this->resolver->format($selector);

        try {
            $missing = ! $this->resolver->findOrFail($selector)->isDisplayed();
        } catch (NoSuchElementException $e) {
            $missing = true;
        }

        PHPUnit::assertTrue($missing, "Saw unexpected element [{$fullSelector}].");

        return $this;
    }