Possible Running Parallelism Locally

Looking to test my phpunit parallelism locally and haven’t had any luck on how to do so. Is it possible to test this locally with multiple containers or does it have to be in production?
Here’s my code
tests:
docker:
- image: my-image
working_directory: ~/project
parallelism: 3
steps:
- checkout
- setup_remote_docker:
version: 17.09.0-ce
docker_layer_caching: true
- restore_cache:
keys:
- composer-install-{{ checksum "composer.lock" }}-{{ checksum "composer.json" }}
- run:
name: Install Composer dependencies.
environment:
COMPOSER_ALLOW_SUPERUSER: 1
command: |
composer install
- save_cache:
key: composer-install-{{ checksum "composer.lock" }}-{{ checksum "composer.json" }}
paths:
- vendor
- run:
name: Create .env file and set values.
command: |
# all my env data
- run:
name: PHPUnit Tests.
command: |
TESTFILES=$(circleci tests glob ./tests/**/**/*.php | circleci tests split --split-by=filesize)
vendor/bin/phpunit ${TESTFILES}
when: on_success