add backend testing.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

.drone.yml

@@ -8,7 +8,6 @@ pipeline:
 
   frontend:
     image: node:8.1.2
-    pull: true
     commands:
       - node -v
       - npm -v
@@ -16,3 +15,11 @@ pipeline:
       - yarn config set cache-folder .yarn-cache
       - yarn install
       - yarn run production
+
+  backend:
+    image: laradock/workspace:1.8-71
+    commands:
+      - php -v
+      - composer -V
+      - composer install --prefer-dist
+      - ./vendor/bin/phpunit