composer/tests/Composer/Test/Installer/Fixtures/installer-v1/Installer/Custom.php

<?php

namespace Installer;

use Composer\Installer\InstallerInterface;
use Composer\Package\PackageInterface;
use Composer\Repository\InstalledRepositoryInterface;

class Custom implements InstallerInterface
{
    public $version = 'installer-v1';

    public function supports($packageType) {}
    public function isInstalled(InstalledRepositoryInterface $repo, PackageInterface $package) {}
    public function install(InstalledRepositoryInterface $repo, PackageInterface $package) {}
    public function update(InstalledRepositoryInterface $repo, PackageInterface $initial, PackageInterface $target) {}
    public function uninstall(InstalledRepositoryInterface $repo, PackageInterface $package) {}
    public function getInstallPath(PackageInterface $package) {}
}