This command check if the files composer.json and bower.json was modified in the previous pull and execute composer install and bower install to update the system dependencies

InstallOnPostMergeCommand.php

<?php
namespace App\Command;

use Symfony\Bundle\FrameworkBundle\Command\ContainerAwareCommand;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;

class InstallOnPostMergeCommand extends ContainerAwareCommand
{
    const COMPOSER_JSON_FILE = 'composer.json';
    const BOWER_JSON_FILE    = 'bower.json';

    /**
     * @inheritDoc
     */

    protected function configure()
    {
        $this
            ->setName('app:post-merge:install')
        ;
    }

    /**
     * @inheritDoc
     */
    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $output->writeln('<fg=yellow;options=bold>Post-Merge Hook</fg=yellow;options=bold>');
        $output->writeln('<info>Check composer</info>');

        $pushedFiles = $this->extractPushedFiles();

        if ($this->checkInstall(self::COMPOSER_JSON_FILE, $pushedFiles)) {
            $output->writeln('<info> Executing composer install </info>');
            exec('composer install  --prefer-dist --optimize-autoloader');
            $output->writeln('<info> composer install finished </info>');
        } else {
            $output->writeln('<info>composer.json isn\'t updated </info>');
        }

        if ($this->checkInstall(self::BOWER_JSON_FILE, $pushedFiles)) {
            $output->writeln('<info> Executing bower install </info>');
            exec('bower install');
            $output->writeln('<info> bower install finished </info>');
        } else {
            $output->writeln('<info>bower.json isn\'t updated </info>');
        }
    }

    private function checkInstall($file, $pushedFiles)
    {
        if (in_array($file, $pushedFiles)) {
            return true;
        }

        return false;
    }

    private function extractPushedFiles()
    {
        $pushedFiles = [];

        exec('git diff-tree -r --name-only --no-commit-id HEAD', $pushedFiles);

        return $pushedFiles;
    }
}