Incorporate MySQL too

Author: danielbachhuber

circle.yml

@@ -5,8 +5,14 @@ jobs:
     parallelism: 1
     docker:
     - image: circleci/php:7.1
+    - image: circleci/mysql:5.6
     steps:
     - checkout
+    - run: |
+        sudo sh -c "printf '\ndeb http://ftp.us.debian.org/debian sid main\n' >> /etc/apt/sources.list"
+        sudo apt-get update
+        sudo docker-php-ext-install mysqli
+        sudo apt-get install mysql-client-5.7
     - run: |
         composer require wp-cli/wp-cli:dev-master
         composer install