// src/Symfony/Component/Console/Tests/Tester/CommandTesterTest.php
    public function testHelpDisplays()
    {
        $command = new Command('foo');
        $command->setCode(function (OutputInterface $output) { $output->writeln('Hello foo!'); });

        $application = new Application();
        $application->setAutoExit(false);
        $application->add($command);

        $tester = new CommandTester($application->find('foo'));
        $tester->execute(['--help' => true]);

        $this->assertStringContainsString('Hello foo!', $tester->getDisplay());
        $this->assertEquals('Hello foo!'.\PHP_EOL, $tester->getDisplay());
    }