Don't load ActiveStorage::Blob when validating the service

For tasks like `assets:precompile` that don't need ActiveStorage, we
should not be loading the entire Active Storage behavior just to be
able to validate the service configuration since Active Storage might
be miss configured for that task.

Author: rafaelfranca

activestorage/app/models/active_storage/blob.rb

@@ -151,22 +151,6 @@ def compose(blobs, key: nil, filename:, content_type: nil, metadata: nil)
         combined_blob.save!
       end
     end
-
-    def validate_service_configuration(service_name, model_class, association_name) # :nodoc:
-      if service_name
-        services.fetch(service_name) do
-          raise ArgumentError, "Cannot configure service #{service_name.inspect} for #{model_class}##{association_name}"
-        end
-      else
-        validate_global_service_configuration
-      end
-    end
-
-    def validate_global_service_configuration # :nodoc:
-      if connected? && table_exists? && Rails.configuration.active_storage.service.nil?
-        raise RuntimeError, "Missing Active Storage service name. Specify Active Storage service name for config.active_storage.service in config/environments/#{Rails.env}.rb"
-      end
-    end
   end
 
   include Analyzable

activestorage/lib/active_storage/attached/changes/create_one.rb

@@ -121,7 +121,7 @@ def attachment_service_name
         service_name = record.attachment_reflections[name].options[:service_name]
         if service_name.is_a?(Proc)
           service_name = service_name.call(record)
-          ActiveStorage::Blob.validate_service_configuration(service_name, record.class, name)
+          Attached::Model.validate_service_configuration(service_name, record.class, name)
         end
         service_name
       end

activestorage/lib/active_storage/attached/model.rb

@@ -106,7 +106,7 @@ module Attached::Model
       # <tt>active_storage_attachments.record_type</tt> polymorphic type column of
       # the corresponding rows.
       def has_one_attached(name, dependent: :purge_later, service: nil, strict_loading: false)
-        ActiveStorage::Blob.validate_service_configuration(service, self, name) unless service.is_a?(Proc)
+        Attached::Model.validate_service_configuration(service, self, name) unless service.is_a?(Proc)
 
         generated_association_methods.class_eval <<-CODE, __FILE__, __LINE__ + 1
           # frozen_string_literal: true
@@ -208,7 +208,7 @@ def #{name}=(attachable)
       # <tt>active_storage_attachments.record_type</tt> polymorphic type column of
       # the corresponding rows.
       def has_many_attached(name, dependent: :purge_later, service: nil, strict_loading: false)
-        ActiveStorage::Blob.validate_service_configuration(service, self, name) unless service.is_a?(Proc)
+        Attached::Model.validate_service_configuration(service, self, name) unless service.is_a?(Proc)
 
         generated_association_methods.class_eval <<-CODE, __FILE__, __LINE__ + 1
           # frozen_string_literal: true
@@ -259,6 +259,25 @@ def #{name}=(attachables)
       end
     end
 
+    class << self
+      def validate_service_configuration(service_name, model_class, association_name) # :nodoc:
+        if service_name
+          ActiveStorage::Blob.services.fetch(service_name) do
+            raise ArgumentError, "Cannot configure service #{service_name.inspect} for #{model_class}##{association_name}"
+          end
+        else
+          validate_global_service_configuration(model_class)
+        end
+      end
+
+      private
+        def validate_global_service_configuration(model_class)
+          if model_class.connected? && ActiveStorage::Blob.table_exists? && Rails.configuration.active_storage.service.nil?
+            raise RuntimeError, "Missing Active Storage service name. Specify Active Storage service name for config.active_storage.service in config/environments/#{Rails.env}.rb"
+          end
+        end
+    end
+
     def attachment_changes # :nodoc:
       @attachment_changes ||= {}
     end

railties/test/application/active_storage/validating_service_test.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+require "isolation/abstract_unit"
+require "rack/test"
+require "rails-dom-testing"
+
+module ApplicationTests
+  class ValidatingServiceTest < ActiveSupport::TestCase
+    include ActiveSupport::Testing::Isolation
+    include Rack::Test::Methods
+    include Rails::Dom::Testing::Assertions
+
+    self.file_fixture_path = "#{RAILS_FRAMEWORK_ROOT}/activestorage/test/fixtures/files"
+
+    def setup
+      build_app
+    end
+
+    def teardown
+      teardown_app
+    end
+
+    def test_boot_application_with_model_using_active_storage_should_not_load_active_storage_blob
+      rails "active_storage:install"
+
+      rails "generate", "model", "user", "name:string", "avatar:attachment"
+      rails "db:migrate"
+
+      app_file "config/routes.rb", <<~RUBY
+        Rails.application.routes.draw do
+          _ = User
+          resources :users, only: [:show, :create]
+          Rails.configuration.ok_to_proceed = true
+        end
+      RUBY
+
+      app_file "config/initializers/active_storage.rb", <<~RUBY
+        Rails.configuration.ok_to_proceed = false
+
+        ActiveSupport.on_load(:active_storage_blob) do
+          raise "ActiveStorage::Blob was loaded" unless Rails.configuration.ok_to_proceed
+        end
+      RUBY
+
+      assert_nothing_raised do
+        with_env "RAILS_ENV" => "production" do
+          rails ["environment", "--trace"]
+        end
+      end
+    end
+  end
+end

railties/test/application/assets_test.rb

@@ -26,13 +26,6 @@ def precompile!(env = nil)
       end
     end
 
-    def with_env(env)
-      env.each { |k, v| ENV[k.to_s] = v }
-      yield
-    ensure
-      env.each_key { |k| ENV.delete k.to_s }
-    end
-
     def clean_assets!
       quietly do
         rails ["assets:clobber"]

railties/test/application/sprockets_assets_test.rb

@@ -56,13 +56,6 @@ def run_app_update
       end
     end
 
-    def with_env(env)
-      env.each { |k, v| ENV[k.to_s] = v }
-      yield
-    ensure
-      env.each_key { |k| ENV.delete k.to_s }
-    end
-
     def clean_assets!
       quietly do
         rails ["assets:clobber"]

railties/test/isolation/abstract_unit.rb

@@ -595,6 +595,14 @@ class ActiveSupport::TestCase
   include TestHelpers::Reload
   include ActiveSupport::Testing::Stream
   include ActiveSupport::Testing::MethodCallAssertions
+
+  private
+    def with_env(env)
+      env.each { |k, v| ENV[k.to_s] = v }
+      yield
+    ensure
+      env.each_key { |k| ENV.delete k.to_s }
+    end
 end
 
 # Create a scope and build a fixture rails app