Sets up a module as an importable module of fixtures.

This module can be used in any module that defines common fixtures to be shared amongst many tests.

By using ExUnitFixtures.FixtureModule a module will become a fixture module. A fixture module can be used by other test cases, as well as imported into other fixture modules.

For example:

defmodule MyFixtures do
  use ExUnitFixtures.FixtureModule

  deffixture database do
    %{db: :db}
  end

  deffixture user(database) do
    %{user: user}
  end
end

defmodule MyTests do
  use ExUnitFixtures
  use MyFixtures
  use ExUnit.Case

  @tag fixtures: [:user]
  test "that we have a user", %{user: user} do
    assert user == :user
  end
end

Overriding Fixtures

When importing fixtures into a module it’s possible to override some of those fixtures, by calling deffixture with an already used name. The overriding fixture may depend on the existing fixture, but any other fixture in the current module or importing modules will only be able to get the overriding fixture.

defmodule MyFixtures do
  use ExUnitFixtures.FixtureModule

  deffixture user do
    make_user()
  end
end

defmodule InactiveUserTests do
  deffixture user(user) do
    %{user | active: false}
  end

  @tag fixtures: [:user]
  test "that user is inactive", %{user: user} do
    assert user.active == false
  end
end

Loading Fixture Code

All the examples in this file have shown a fixture module defined within the same file as the tests. This is not too likely to happen in an actual project. It’s more likely that you’d want to define a fixture module in one file and then import it into many other files.

By default ExUnitFixtures makes this fairly easy - any file named fixtures.exs in any folder underneath test/ will automatically be loaded into the VM when calling ExUnitFixtures.start/1.

Any fixture modules defined within these files will also automatically be imported into the current module as documented in ExUnitFixtures.AutoImport.

If you wish to load in fixtures that are not contained within a fixtures.exs file, then you should load them into the VM with Code.require_file in your test_helpers.exs and then manually use the fixture module.