public function testExecutionFailed()
 {
     $cmd = new Command('echo "Execution Failed');
     $cmd->run();
     $this->assertTrue($cmd->hasFuture());
     $this->assertFalse($cmd->getFuture()->isExecuted());
     $this->assertNotNull($cmd->getFuture()->getResult());
     $this->assertTrue($cmd->getFuture()->isExecuted());
     $this->assertNotNull($cmd->getExecutionResult());
     $this->assertNotEmpty($cmd->getExecutionResult()->getStderr());
     $this->assertNotEquals($cmd->getExecutionResult()->getExitCode(), 0);
 }