src/Printer.php
protected function onAddFailure($e)
    {
        $this->writeProgressWithColor('fg-red,bold', 'F');

        $this->failure = $e;
        $this->lastTestFailed = true;
        $this->flawless = false;
    }
protected function onAddFailure($e)
    {
        $this->writeProgressWithColor('fg-red,bold', 'F');

        $this->failure = $e;
        $this->lastTestFailed = true;
        $this->flawless = false;
    }
Invoked when an assertion fails in the test runner.

@param AssertionFailedError $e