scripts/ScriptHandler.php
public static function checkComposerVersion(Event $event) {
    $composer = $event->getComposer();
    $io = $event->getIO();

    $version = $composer::VERSION;

    // If Composer is installed through git we have no easy way to determine if
    // it is new enough, just display a warning.
    if ($version === '@package_version@') {
      $io->writeError('<warning>You are running a development version of Composer. If you experience problems, please update Composer to the latest stable version.</warning>');
    }
    elseif (Comparator::lessThan($version, '1.0.0')) {
      $io->writeError('<error>UpMembership requires Composer version 1.0.0 or higher. Please update your Composer before continuing</error>.');
      exit(1);
    }
  }
public static function checkComposerVersion(Event $event) {
    $composer = $event->getComposer();
    $io = $event->getIO();

    $version = $composer::VERSION;

    // If Composer is installed through git we have no easy way to determine if
    // it is new enough, just display a warning.
    if ($version === '@package_version@') {
      $io->writeError('<warning>You are running a development version of Composer. If you experience problems, please update Composer to the latest stable version.</warning>');
    }
    elseif (Comparator::lessThan($version, '1.0.0')) {
      $io->writeError('<error>UpMembership requires Composer version 1.0.0 or higher. Please update your Composer before continuing</error>.');
      exit(1);
    }
  }
public static function checkComposerVersion ( Event $ event ) { $ composer = $ event -> getComposer ( ) ; $ io = $ event -> getIO ( ) ; $ version = $ composer :: VERSION ; // If Composer is installed through git we have no easy way to determine if // it is new enough, just display a warning. if ( $ version === '@package_version@' ) { $ io -> writeError ( '<warning>You are running a development version of Composer. If you experience problems, please update Composer to the latest stable version.</warning>' ) ; } elseif ( Comparator :: lessThan ( $ version , '1.0.0' ) ) { $ io -> writeError ( '<error>UpMembership requires Composer version 1.0.0 or higher. Please update your Composer before continuing</error>.' ) ; exit ( 1 ) ; } }
Checks if the installed version of Composer is compatible.

Composer 1.0.0 and higher consider a `composer install` without having a
lock file present as equal to `composer update`. We do not ship with a lock
file to avoid merge conflicts downstream, meaning that if a project is
installed with an older version of Composer the scaffolding of Drupal will
not be triggered. We check this here instead of in drupal-scaffold to be
able to give immediate feedback to the end user, rather than failing the
installation after going through the lengthy process of compiling and
downloading the Composer dependencies.

@see https://github.com/composer/composer/pull/5035
Checks if the installed version of Composer is compatible .