Material for Synbioz blog post on Elixir tests

Welcome on this Github repository. Chance are you've been coming from the Synbioz blog post on tests with Elixir (french version).

This project is an example of Elixir tests driven by tags. You can directly watch the file test/elixir_unit_tests_test.exs.

Want to play with the project ? Follow the guide.

Requirements

You can use your current setup with Elixir or choose a Docker image, choice is yours:

To try the project on your system, you must have:

• Elixir (1.10)
• Postgresql (with a database up)

Or you can experiment through a Docker image containing the above requirements. We will see how a little further. Be sure to have Docker on your system.

Installation of Elixir or Docker is out of the scope for this Readme.

Get the project's files on your computer

Download the zip file of this project or use Git to clone the repository:

git clone https://github.com/ludovicdeluna/elixir_unit_tests.git
cd elixir_unit_tests

Prepare your system

Skip this section if you use the Docker image - all the requirements are already in the image.

The instructions target a Unix compliant system (Linux / BSD or MacOS).

First, get the generic dependencies bellow. If you use the Phoenix framework or Ecto, it's possible you already have them on your computer.

mix local.rebar
mix local.hex --force

Second, set your Mix env to test:

export MIX_ENV=test

Finally, configure the config/test.exs file to let the project contact your Postgresql database, especially the fields username, password and hostname. If your database use an unusual port, add port entry.

Congratulations, you are now ready for the next part.

Get dependancies

You have to get the dependencies the first time you play:

# (from the root project)
mix deps.get

Run the test

This project is configured to automatically prepare your database and apply schema migrations before the tests run:

# (from the root project)
mix test

It's your first try with Elixir ? The code is firstly compiled to bytecode for the BEAM VM then the VM execute the program. Compilation occurs every time the source code change.

Nothing more for now. The file mentioned in the blog post is test/elixir_unit_tests_test.exs. Don't hesitate to experiment.

Have a fun !

Docker

This part explain you how to build and start a Docker image with all the requirement inside it. Before start, check that your Docker client use the Linux mode by default for your images. This is the case if you have never changed your settings.

The build process use Linux Alpine with Elixir 1.10 and Postgresql. The build do the following actions:

• run the PG scripts to setup a default database;
• get the default dependencies for Elixir;
• add the MIX_ENV to test.
• set the default action to start Posgresql and open an interactive shell.

The final image size is 148Mb (nammed elixir_unit_tests_app).

You can build the image and run the container with Docker Compose or with plain Docker's commands.

Method 1 - with docker-compose:

docker-compose build
docker-compose run --rm app

Method 2 - plain docker commands:

docker build -t elixir_unit_tests_app:latest .

docker run -it \
  --name elixir_unit_tests \
  --rm \
  --volume $(pwd):/app \
  elixir_unit_tests_app

For the two methods, you will see this last lines on your screen:

server started
/app #

Your are now ready for the next step. Type exit if you want to quit the container.