.gitlab-ci.yml

stages:
  - test

phpunit:
  stage: test
  image: php:7.1-cli
  only:
    - master
  script:
    - apt-get update
    - apt-get install -y unzip
    - curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/bin --filename=composer
    - composer self-update
    - composer install --prefer-dist > /dev/null
    - php vendor/bin/phpunit --colors --debug  --coverage-text

phpunit.xml

<?xml version="1.0" encoding="UTF-8"?>
<phpunit colors="true" syntaxCheck="true" verbose="true">
    <testsuites>
        <testsuite name="Composer Test Suite">
            <directory>./src/</directory>
        </testsuite>
    </testsuites>
</phpunit>