Activestorage fixtures attachments

Question

In rails tests. I have a basic model with only activestorage:

class User < ApplicationRecord
  has_one_attached :avatar
end

I\'m trying

Answer 1

Lets say you have a test for the model user, the default UserTest#test_the_truth

rails test test/models/user_test.rb

I suppose you are getting an error Errno::ENOENT: No such file or directory @ rb_sysopen during the test, because of an error in your path, you must add 'fixtures', it should be like:

# users.yml
one:
  name: 'Jim Kirk'
  avatar: <%= File.open Rails.root.join('test', 'fixtures', 'files', 'image.png').to_s %>

but now you should have this error: ActiveRecord::Fixture::FixtureError: table "users" has no column named "avatar".

That's correct, because ActiveStorage uses two tables to work: active_storage_attachments and active_storage_blobs.

---

So, you need to remove avatar column from users.yml and add two new files:

(Disclaimer See also comments below: "no need create own models, so instead of ActiveStorageAttachment you could use original ActiveStorage::Attachment and place fixture under active_storage folder" and refer also to https://stackoverflow.com/a/55835955/5239030)

# active_storage_attachments.yml
one:
  name: 'avatar'
  record_type: 'User'
  record_id: 1
  blob_id: 1

and

# active_storage_blobs.yml
one:
  id: 1
  key: '12345678'
  filename: 'file.png'
  content_type: 'image/png'
  metadata: nil
  byte_size: 2000
  checksum: "123456789012345678901234"

Also, in App/models, add, even if not required for the ActiveStorage to work.

# active_storage_attachment.rb
class ActiveStorageAttachment < ApplicationRecord
end

and

# active_storage_blob.rb
class ActiveStorageBlob < ApplicationRecord
end

---

Then the UserTest#test_the_truth succeed.

But better get rid of active_storage_attachment.rb and active_storage_blob.rb and follow another way to test.

For testing if the attachment is working, better test the controller, for example adding this code in test/controllers/users_controller_test.rb:

require 'test_helper'

class UserControllerTest < ActionController::TestCase
  def setup
    @controller = UsersController.new
  end
  test "create user with avatar" do
    user_name = 'fake_name'
    avatar_image = fixture_file_upload(Rails.root.join('test', 'fixtures', 'files', 'avatar.png'),'image/png')
    post :create, params: {user: {name: user_name, avatar: avatar_image}}
  end
end

Check the folder tmp/storage, should be empty.

Launch the test with: rails test test/controllers/users_controller_test.rb

It should succeed, then if you check again in tmp/storage, you should find some folders and files generated by the test.

Edit after comments: If you need to test the callbacks on User model, then this should work:

# rails test test/models/user_test.rb

require 'test_helper'

class UserTest < ActiveSupport::TestCase
  test "should have avatar attached" do
    u = User.new
    u.name = 'Jim Kirk'
    file = Rails.root.join('test', 'fixtures', 'files', 'image.png')
    u.avatar.attach(io: File.open(file), filename: 'image.png') # attach the avatar, remove this if it is done with the callback
    assert u.valid?
    assert u.avatar.attached? # checks if the avatar is attached
  end
end

I don't know your callback, but I hope this gives you some hint.