How to set up namespaced model fixtures in Rails 7 Minitest?

Question

I've a similar issue like this old one related to using namespaced model fixtures for a has_one-belongs_to association in Rails 7.

About ActiveRecord, in my model files I've:

# app/models/user.rb
class User < ApplicationRecord
  has_one :setting, :class_name  => 'Users::Setting', :foreign_key => 'user_id'
end

# app/models/users/setting.rb
class Users::Setting < ApplicationRecord
  belongs_to :user, :class_name  => 'User', :foreign_key => 'user_id'
end

# app/models/users.rb
module Users
  def self.table_name_prefix
    'users_'
  end
end

About fixtures, in the test/fixtures/users.yml file I've created and successfully used the following for the User model:

# test/fixtures/users.yml

foo:
  id: 1
  name: Foo
  email: foo@bar.com
  ...

bar:
  id: 2
  name: Bar
  email: bar@foo.com
  ...

However I'm in trouble in setting up fixtures for the Users::Setting model. I tried to create the test/fixtures/users/settings.yml file and to use the following without success:

# test/fixtures/users/settings.yml

_fixture:
  model_class: Users::Setting

foo_setting:
  id: 1
  user_id: 1
  ...

# foo_setting:
#   id: 1
#   user: foo
#   ...

When I run a test, I get errors as follows:

Minitest::UnexpectedError: ActiveRecord::Fixture::FixtureError: table "users" has no columns named "user_id"/"user".

In the User fixtures I also tried to use the following but I get the same Minitest error:

# test/fixtures/users.yml

foo:
  id: 1
  name: Foo
  email: foo@bar.com
  setting: foo_setting (Users:Setting) # <<<
  ...

I also tried to edit the test/test_helper.rb file like so but I get the same Minitest error:

class ActiveSupport::TestCase
  fixtures :all
  set_fixture_class 'users/settings' => Users::Setting
end

In test/integration/user_flows_test.rb I've:

# test/integration/user_flows_test.rb

require "test_helper"

class UserFlowsTest < ActionDispatch::IntegrationTest
  fixtures :users

  test "can something" do
    user = users(:foo)
    ...
  end
end

How can I state working fixtures for the namespaced Users::Setting?

Answer 1

Found a solution:

1. In test/test_helper.rb I added set_fixture_class :users_settings => Users::Setting

test/test_helper.rb

class ActiveSupport::TestCase
  ...

  # Setup all fixtures in test/fixtures/*.yml for all tests in alphabetical order.
  fixtures :all

  # Namespaced models/fixtures
  set_fixture_class :users_settings => Users::Setting

  ...
end

2. (Re)Named the file that contains the fixture statement as users_settings.yml
3. Located the file users_settings.yml at test/fixtures/users_settings.yml