Awesome
Testcontainers
Testcontainers is an Elixir library that supports ExUnit tests, providing lightweight, throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.
Table of Contents
Prerequisites
Before you begin, ensure you have met the following requirements:
- You have installed the latest version of Elixir
- You have a Docker runtime installed
- You are familiar with Elixir and Docker basics
Installation
To add Testcontainers to your project, follow these steps:
- Add
testcontainers
to your list of dependencies inmix.exs
:
def deps do
[
{:testcontainers, "~> 1.11"}
]
end
-
Run mix deps.get
-
Add the following to test/test_helper.exs
Testcontainers.start_link()
Usage
This section explains how to use the Testcontainers library in your own project.
Basic usage
You can use generic container api, where you have to define everything yourself:
{:ok, _} = Testcontainers.start_link()
config = %Testcontainers.Container{image: "redis:5.0.3-alpine"}
{:ok, container} = Testcontainers.start_container(config)
Or you can use one of many predefined containers like RedisContainer
, that has waiting strategies among other things defined up front with good defaults:
{:ok, _} = Testcontainers.start_link()
config = Testcontainers.RedisContainer.new()
{:ok, container} = Testcontainers.start_container(config)
If you want to use a predefined container, such as RedisContainer
, with an alternative image, for example, valkey/valkey
, it's possible:
{:ok, _} = Testcontainers.start_link()
config =
Testcontainers.RedisContainer.new()
|> Testcontainers.RedisContainer.with_image("valkey/valkey:latest")
|> Testcontainers.RedisContainer.with_check_image("valkey/valkey")
{:ok, container} = Testcontainers.start_container(config)
ExUnit tests
Given you have added Testcontainers.start_link() to test_helper.exs:
setup
config = Testcontainers.RedisContainer.new()
{:ok, container} = Testcontainers.start_container(config)
ExUnit.Callbacks.on_exit(fn -> Testcontainers.stop_container(container.container_id) end)
{:ok, %{redis: container}}
end
there is a macro that can simplify this down to a oneliner:
import Testcontainers.ExUnit
container(:redis, Testcontainers.RedisContainer.new())
Run tests in a Phoenix project (or any project for that matter)
To run/wrap testcontainers around a project use the testcontainers.test task.
mix testcontainers.test [--database postgres|mysql] [--watch dir ...]
to use postgres you can just run
mix testcontainers.test
since postgres is default.
in your config/test.exs you can then change the repo config to this:
config :my_app, MyApp.Repo,
username: System.get_env("DB_USER") || "postgres",
password: System.get_env("DB_PASSWORD") || "postgres",
hostname: System.get_env("DB_HOST") || "localhost",
port: System.get_env("DB_PORT") || "5432",
database: "my_app_test#{System.get_env("MIX_TEST_PARTITION")}",
pool: Ecto.Adapters.SQL.Sandbox,
pool_size: System.schedulers_online() * 2
Activate reuse of database containers started by mix task with adding testcontainers.reuse.enable=true
in ~/.testcontainers.properties
. This is experimental.
You can pass arguments to mix test by append -- to the of the command like this:
mix testcontainers.test -- --exclude flaky --stale
In the example above we are excluding flaky tests and using the --stale option.
Logging
Testcontainers use the standard Logger, see https://hexdocs.pm/logger/Logger.html.
API Documentation
For more detailed information about the API, different container configurations, and advanced usage scenarios, please refer to the API documentation.
Contributing
We welcome your contributions! Please see our contributing guidelines (TBD) for more details on how to submit patches and the contribution workflow.
License
Testcontainers is available under the MIT license. See the LICENSE file for more info.
Contact
If you have any questions, issues, or want to contribute, feel free to contact us.
Thank you for using Testcontainers to test your Elixir applications!