Require that load_defaults is called

After all the initializers are run, we check that the application called
`#load_defaults` method for every Solidus engine and, otherwise, show a
deprecation message. This is done as a security check to ensure that
users are conscious about which Solidus version defaults are using. If
they didn't call it, it would default to the latest Solidius version,
which could break their code if they didn't update through the
`solidus:update` generator.

api/spec/spec_helper.rb

@@ -13,7 +13,7 @@
 DummyApp.setup(
   gem_root: File.expand_path('..', __dir__),
   lib_name: 'solidus_api'
-)
+) { Spree::Api::Config.load_defaults(Spree.solidus_version) }
 
 require 'rails-controller-testing'
 require 'rspec/rails'

backend/spec/spec_helper.rb

@@ -14,7 +14,10 @@
 DummyApp.setup(
   gem_root: File.expand_path('..', __dir__),
   lib_name: 'solidus_backend'
-)
+) do
+  Spree::Backend::Config.load_defaults(Spree.solidus_version)
+  Spree::Api::Config.load_defaults(Spree.solidus_version)
+end
 
 require 'rails-controller-testing'
 require 'rspec-activemodel-mocks'

core/lib/generators/solidus/update/templates/config/initializers/new_solidus_defaults.rb.tt

@@ -2,7 +2,9 @@
 # Solidus version.
 #
 # It allows you to enable them one by one while you adapt your application.
-# When you're done with all of them, you can safely remove this file.
+# When you're done with all of them, you can safely remove this file and add
+# the updated `load_defaults` calls to the top of the config blocks in your
+# Solidus main initializer.
 Spree.config do |config|
   <%= @core_changes %>
 end

core/lib/spree/core/engine.rb

@@ -63,6 +63,13 @@ class Engine < ::Rails::Engine
         app.config.action_mailer.preview_path = "{#{original_preview_path},#{solidus_preview_path}}"
         ActionMailer::Base.preview_path = app.config.action_mailer.preview_path
       end
+
+      config.after_initialize do
+        Spree::Config.check_load_defaults_called('Spree::Config')
+        Spree::Frontend::Config.check_load_defaults_called('Spree::Frontend::Config') if defined?(Spree::Frontend::Engine)
+        Spree::Backend::Config.check_load_defaults_called('Spree::Backend::Config') if defined?(Spree::Backend::Engine)
+        Spree::Api::Config.check_load_defaults_called('Spree::Api::Config') if defined?(Spree::Api::Engine)
+      end
     end
   end
 end

core/lib/spree/preferences/configuration.rb

@@ -38,18 +38,35 @@ class Configuration
     #     defaults. Set via {#load_defaults}
     attr_reader :loaded_defaults
 
+    attr_reader :load_defaults_called
+
     def initialize
       @loaded_defaults = Spree.solidus_version
+      @load_defaults_called = false
     end
 
     # @param [String] Solidus version from which take defaults when not
     # overriden.
     # @see #load_defaults
     def load_defaults(version)
       @loaded_defaults = version
+      @load_defaults_called = true
       reset
     end
 
+    def check_load_defaults_called(instance_constant_name = nil)
+      return if load_defaults_called
+
+      target_name = instance_constant_name || "#{self.class.name}.new"
+      Spree::Deprecation.warn <<~MSG
+        Please, indicate wich Solidus version defaults the application must use.
+        The method `#{target_name}.load_defaults` must be called from the Solidus initializer. E.g.:
+
+          config.load_defaults('#{Spree.solidus_version}')
+
+      MSG
+    end
+
     # @yield [config] Yields this configuration object to a block
     def configure
       yield(self)

core/lib/spree/testing_support/dummy_app.rb

@@ -34,9 +34,10 @@ module ApplicationHelper
 
 # @private
 module DummyApp
-  def self.setup(gem_root:, lib_name:, auto_migrate: true)
+  def self.setup(gem_root:, lib_name:, auto_migrate: true, &block)
     ENV["LIB_NAME"] = lib_name
     DummyApp::Application.config.root = File.join(gem_root, 'spec', 'dummy')
+    block.call if block_given?
 
     DummyApp::Application.initialize!
 
@@ -119,6 +120,7 @@ class Application < ::Rails::Application
 
 Spree.user_class = 'Spree::LegacyUser'
 Spree.config do |config|
+  config.load_defaults(Spree.solidus_version)
   config.mails_from = "[email protected]"
 
   if ENV['DISABLE_ACTIVE_STORAGE']

core/spec/models/spree/preferences/configuration_spec.rb

@@ -3,52 +3,85 @@
 require 'rails_helper'
 
 RSpec.describe Spree::Preferences::Configuration, type: :model do
-  before :all do
-    class AppConfig < Spree::Preferences::Configuration
+  let(:config) do
+    Class.new(Spree::Preferences::Configuration) do
       preference :color, :string, default: :blue
       preference :foo, :boolean, default: by_version(true, "3.0" => false)
-    end
-    @config = AppConfig.new
+    end.new
   end
 
   it "has named methods to access preferences" do
-    @config.color = 'orange'
-    expect(@config.color).to eq 'orange'
+    config.color = 'orange'
+    expect(config.color).to eq 'orange'
   end
 
   it "uses [ ] to access preferences" do
-    @config[:color] = 'red'
-    expect(@config[:color]).to eq 'red'
+    config[:color] = 'red'
+    expect(config[:color]).to eq 'red'
   end
 
   it "uses set/get to access preferences" do
-    @config.set(color: 'green')
-    expect(@config.get(:color)).to eq 'green'
+    config.set(color: 'green')
+    expect(config.get(:color)).to eq 'green'
   end
 
   it "allows defining different defaults depending on the Solidus version" do
-    @config.load_defaults 2.1
+    config.load_defaults 2.1
 
-    expect(@config.get(:foo)).to be(true)
+    expect(config.get(:foo)).to be(true)
 
-    @config.load_defaults 3.1
+    config.load_defaults 3.1
 
-    expect(@config.get(:foo)).to be(false)
+    expect(config.get(:foo)).to be(false)
   end
 
   describe '#load_defaults' do
     it 'changes loaded_defaults' do
-      @config.load_defaults '2.1'
+      config.load_defaults '2.1'
 
-      expect(@config.loaded_defaults).to eq('2.1')
+      expect(config.loaded_defaults).to eq('2.1')
 
-      @config.load_defaults '3.1'
+      config.load_defaults '3.1'
 
-      expect(@config.loaded_defaults).to eq('3.1')
+      expect(config.loaded_defaults).to eq('3.1')
     end
 
     it 'returns updated preferences' do
-      expect(@config.load_defaults('2.1')).to eq(foo: true, color: :blue)
+      expect(config.load_defaults('2.1')).to eq(foo: true, color: :blue)
+    end
+
+    it 'sets load_defaults_called flag to true' do
+      expect(config.load_defaults_called).to be(false)
+
+      config.load_defaults '3.1'
+
+      expect(config.load_defaults_called).to be(true)
+    end
+  end
+
+  describe '#check_load_defaults_called' do
+    context 'when load_defaults_called is true' do
+      it 'does not emit a warning' do
+        config.load_defaults '3.1'
+
+        expect(Spree::Deprecation).not_to receive(:warn)
+
+        config.check_load_defaults_called
+      end
+    end
+
+    context 'when load_defaults_called is false' do
+      it 'emits a warning' do
+        expect(Spree::Deprecation).to receive(:warn).with(/load_defaults.*must be called/)
+
+        config.check_load_defaults_called
+      end
+
+      it 'includes constant name in the message when given' do
+        expect(Spree::Deprecation).to receive(:warn).with(/Spree::Config.load_defaults/, any_args)
+
+        config.check_load_defaults_called('Spree::Config')
+      end
     end
   end
 end

frontend/spec/spec_helper.rb

@@ -14,7 +14,10 @@
 DummyApp.setup(
   gem_root: File.expand_path('..', __dir__),
   lib_name: 'solidus_frontend'
-)
+) do
+  Spree::Api::Config.load_defaults(Spree.solidus_version)
+  Spree::Frontend::Config.load_defaults(Spree.solidus_version)
+end
 
 require 'rails-controller-testing'
 require 'rspec/rails'