ExampleTest fails in Gitlab CI

Hi folks,

I built a simple gitlab ci with the following docker container:

# Set the base image for subsequent instructions
FROM php:7.1

# Update packages
RUN apt-get update

# Install PHP and composer dependencies
RUN apt-get install git curl libmcrypt-dev libjpeg-dev libpng-dev libfreetype6-dev libbz2-dev -yqq

# Clear out the local repository of retrieved package files
RUN apt-get clean

# Install needed extensions
# Here you can install any other extension that you need during the test and deployment process
RUN docker-php-ext-install exif mcrypt pdo_mysql zip

# Install Composer
RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer

# Install Laravel Envoy
RUN composer global require "laravel/envoy"

with this gitlab-ci.yml:

image: registry.gitlab.com/treenio/treenio:latest

stages:
  - test
  - deploy

cache:
  paths:
  - vendor/

before_script:
    - cp .env.example .env
    - composer install

phpcs:
  stage: test
  script:
    - vendor/bin/phpcs

unit_test:
  stage: test
  script:
    - php artisan key:generate
    - vendor/bin/phpunit

When running the test locally everything works fine. As well with the docker container locally.

But in the Gitlab CI the ExampleTest fails with a 500 instead of a 200 status code. All other tests are green.

There was 1 failure:

1) Tests\Feature\ExampleTest::testBasicTest
Expected status code 200 but received 500.
Failed asserting that false is true.

/builds/treenio/treenio/vendor/laravel/framework/src/Illuminate/Foundation/Testing/TestResponse.php:77
/builds/treenio/treenio/tests/Feature/ExampleTest.php:25

FAILURES!
Tests: 5, Assertions: 7, Failures: 1.
ERROR: Job failed: exit code 1

Anyone any suggestions why the test fails in the CI ?

Thanks in advance bambamboole