Adding composer script for "cms-install"

circle.yml

@@ -48,21 +48,15 @@ dependencies:
     - cgr "drush/drush:~8"
     - mkdir -p ~/.terminus/plugins
     - composer create-project -n -d ~/.terminus/plugins pantheon-systems/terminus-build-tools-plugin:^1
+    - composer create-project -n -d ~/.terminus/plugins pantheon-systems/terminus-composer-plugin:^1
     - composer create-project -n -d ~/.terminus/plugins pantheon-systems/terminus-secrets-plugin:^1
   post:
     - terminus auth:login -n --machine-token="$TERMINUS_TOKEN"
     - terminus build-env:delete:ci -n "$TERMINUS_SITE" --keep=2 --yes
     - composer -n build-assets
     - terminus env:wake -n "$TERMINUS_SITE.dev"
     - terminus build-env:create -n "$TERMINUS_SITE.dev" "$TERMINUS_ENV" --yes --notify="$NOTIFY"
-    - |
-      if [ ! -f "config/system.site.yml" ] ; then
-        terminus drush "$TERMINUS_SITE.$TERMINUS_ENV" -- site-install standard --yes --site-name="$TEST_SITE_NAME" --account-mail="$ADMIN_EMAIL" --account-pass="$ADMIN_PASSWORD"
-        terminus drush -n "$TERMINUS_SITE.$TERMINUS_ENV" -- pm-enable --yes config_direct_save
-      else
-        chmod +w web/sites/default web/sites/default/settings.php
-        terminus drush "$TERMINUS_SITE.$TERMINUS_ENV" -- site-install config_installer --yes --site-name="$TEST_SITE_NAME" --account-mail="$ADMIN_EMAIL" --account-pass="$ADMIN_PASSWORD"
-      fi
+    - terminus composer "$TERMINUS_SITE.$TERMINUS_ENV" cms-install
 test:
   override:
     - run-behat

composer.json

@@ -54,6 +54,7 @@
     "drupal-unit-tests": "cd web/core && ../../vendor/bin/phpunit --testsuite=unit --exclude-group Composer,DependencyInjection,PageCache",
     "drupal-scaffold": "DrupalComposer\\DrupalScaffold\\Plugin::scaffold",
     "prepare-for-pantheon": "DrupalProject\\composer\\ScriptHandler::prepareForPantheon",
+    "cms-install": "drush site-install standard -y",
     "post-install-cmd": [
       "@drupal-scaffold",
       "DrupalProject\\composer\\ScriptHandler::createRequiredFiles"