Testing the untestable: Test network kill during execute

network-kill-execute.php

<?php

public function testNetworkKillerExecute()
{
  $conn = $this->getConnection();
  // sleep 1 second before killing, then kill it for 3 seconds
  exec('php killNetwork.php 1 3 > /dev/null &');
  ErrorHandler::register(null, true);
  // sleep a while to make sure the connection is terminated
  sleep(2);
  $stmt = $conn->query('SELECT NOW();');
  self::expectException(\ErrorException::class);
  self::expectExceptionMessage('Warning: PDOStatement::execute(): MySQL server has gone away');
  $stmt->execute();
}