Elixir / Phoenix - Run code at the very beginning of a test run, shared data for ALL tests

Question

I'd like to run a block of code right at the beginning of my test suite (that inserts data into the database!), and persists across the entirety of the test suite.

Is something like this possible?

I tried running the code in a setup_all block, but: A) I was getting failures trying to insert into the database here; B) This would only be shared between that test module, whereas I'd like it to be shared across all tests.

Thanks for your help!

Answer 1

Run once before starting tests

Just put the common code in your test/test_helper.exs:

ExUnit.start()

# Common Code
ModuleOne.some_method
ModuleTwo.other_method(args) # etc

---

Run before every test

Assuming you have already worked out cleaning up the db and running migrations between tests, you can put something like this in your test/test_helper.exs:

defmodule TestProject.Helpers do
  def setup do
    # Common Code
  end
end

And use this setup block in all of your tests:

setup do
  TestProject.Helpers.setup
end

---

Setting up a Test Database / Schema

If you also need to set up a fake Database, Schema and Migrations for your tests, you'll need to define them as well, and put this in your test_helper (assuming here that the driver you are using is Postgrex):

# Start Ecto
{:ok, _} = Ecto.Adapters.Postgres.ensure_all_started(TestProject.Repo, :temporary)
_        = Ecto.Adapters.Postgres.storage_down(TestProject.Repo.config)
:ok      = Ecto.Adapters.Postgres.storage_up(TestProject.Repo.config)
{:ok, _} = TestProject.Repo.start_link

For a more detailed example, you can see my Ecto.Rut package that creates a fake database (for the test env only), and resets it before running each test.