Fix NoMethodError in ActiveStorage::TransformJob for untracked variants.

[bryantraywick]

Motivation / Background

This Pull Request has been created because a NoMethodError: private method `process' called for #<ActiveStorage::Variant error is raised in ActiveStorage::TransformJob when variant tracking is disabled. This prevents the ability to use preprocessed variants when variant tracking is disabled.

Detail

This Pull Request changes the call to process in ActiveStorage::TransformJob to the processed method which is publicly available in both the ActiveStorage::VariantWithRecord and ActiveStorage::Variant classes.

Additional information

The following code snipped contains a working recreation of the issue with the current main branch.

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "rails", github: "rails/rails", branch: "main"
  gem "rack", "~> 2.0"
  gem "sqlite3"
  gem 'image_processing', '~> 1.2'
end

require "active_record/railtie"
require "active_storage/engine"
require "tmpdir"

class TestApp < Rails::Application
  config.root = __dir__
  config.hosts << "example.org"
  config.eager_load = false
  config.session_store :cookie_store, key: "cookie_store_key"
  config.secret_key_base = "secret_key_base"

  config.logger = Logger.new($stdout)
  Rails.logger  = config.logger

  config.active_storage.service = :local
  config.active_storage.service_configurations = {
    local: {
      root: Dir.tmpdir,
      service: "Disk"
    }
  }

  config.active_storage.track_variants = false
end

ENV["DATABASE_URL"] = "sqlite3::memory:"

Rails.application.initialize!

require ActiveStorage::Engine.root.join("db/migrate/20170806125915_create_active_storage_tables.rb").to_s

ActiveRecord::Schema.define do
  CreateActiveStorageTables.new.change

  create_table :users, force: true
end

class User < ActiveRecord::Base
  has_one_attached :profile do |attachable|
    attachable.variant :test, resize_to_limit: [100, 100], preprocessed: true
  end
end

require "minitest/autorun"

class BugTest < Minitest::Test
  def test_upload_and_download
    user = User.create!(
      profile: {
        content_type: "image/jpeg",
        filename: "racecar.jpg",
        io: Pathname.new("activestorage/test/fixtures/files/racecar.jpg").open,
      }
    )

    assert_equal false, user.profile.variant(:test).send(:processed?)

    user.profile.attachment.send(:named_variants).each do |_name, named_variant|
      assert_raises(NoMethodError) do
        ActiveStorage::TransformJob.perform_now(user.profile, named_variant.transformations)
      end
    end
  end
end

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Changes that are unrelated should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug or add a feature.
• CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.