machine:
  php:
    version: 5.6.14

test:
  pre:
    - bash bin/install-wp-tests.sh wordpress_test root '' localhost latest
  override:
    - phpunit

machine:
  php:
    version: 5.6.22

test:
  pre:
    - bash bin/install-wp-tests.sh wordpress_test root '' localhost latest
  override:
    - phpunit

Use PHP version specific to Trusty
Use PHP version specific to Trusty

Circle is using Trusty by default on new projects
