# Distributed Tests Mix Task

**URL:** <https://forum.elixirforum.com/t/distributed-tests-mix-task/3409>\
**Category:** Announcing\
**Tags:** mix, library, distributed-systems, exunit\
**Created:** [January 25, 2017, 2:45pm UTC](https://forum.elixirforum.com/t/distributed-tests-mix-task/3409 "2017-01-25T14:45:46Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![sschneider](https://forum.elixirforum.com/letter_avatar_proxy/v4/letter/s/848f3c/32.png) [@sschneider](https://forum.elixirforum.com/u/sschneider)\
**Post date:** [January 25, 2017, 2:45pm UTC](https://forum.elixirforum.com/t/distributed-tests-mix-task/3409/1 "2017-01-25T14:45:46Z")

</div>

Lately I’ve been working on more distributed applications, and I was struggling to come up with an easy way of testing them with ExUnit. I looked how Phoenix [PubSub does theirs](https://github.com/phoenixframework/phoenix_pubsub/tree/master/test/support) and it seemed fairly simple so I pulled it out into a mix task. I figured other people might have a use for this as well so I [published it on hex with the name `distributed_test`](https://hex.pm/packages/distributed_test).

It’s pretty simple to use, just run `mix test.distributed [--count N]` and a clustered environment with your app loaded on every node will be started before your tests are ran.

There’s also a helper module in it `DistributedEnviroment` that has a `start/1` and `stop/0` function you can use when developing to quickly start up N number of nodes with your application loaded.

There’s a small gotcha with this in that if you define code in your `test_helper.exs`, it will only be loaded on the master node, so you’ll want to do something like this in your helper file:

```elixir
defmodule Utils do
  @module (quote do
    defmodule Foo do
      # ...
    end
  end)

  def load_foo() do
    Code.eval_quoted(@module)
    Node.list()
    |> Enum.each(&:rpc.block_call(&1, Code, :eval_quoted, [@module]))
  end
end

```

and call `Utils.load_foo()` in your test/in the helper if you need code loaded on all nodes.