Fallback to EnvironmentContainer if assets_manifest is not supported

Support for `Rails.application.assets_manifest` which is used by
`ServerRendering::ManifestContainer` has only been added in
sprockets-rails 2.2.2. Rails 4.0.5 depends on sprockets ~> 2.0.0.

* Feature detect if `assets_manifest` is present
* Add appraisal to test with rails-sprockets < 2.2.2

Author: tf

Appraisals

@@ -7,6 +7,15 @@ appraise "rails-4.0" do
   gem 'rails', '~> 4.0.13'
 end
 
+appraise "rails-4.0.5" do
+  # Depends on sprockets-rails ~> 2.0.0. Support for
+  # `Rails.application.assets_manifest` which is used by
+  # `ServerRendering::ManifestContainer` has only been added in
+  # sprockets-rails 2.2.2. Ensure that server rendering falls back to
+  # `ServerRendering::EnvironmentContainer`.`
+  gem 'rails', '4.0.5'
+end
+
 appraise "rails-4.0-with-therubyracer" do
   gem 'rails', '~> 4.0.13'
   gem 'therubyracer', '0.12.0', :platform => :mri

gemfiles/rails_4.0.5.gemfile

@@ -0,0 +1,7 @@
+# This file was generated by Appraisal
+
+source "http://rubygems.org"
+
+gem "rails", "4.0.5"
+
+gemspec :path => "../"

lib/react/server_rendering/manifest_container.rb

@@ -14,6 +14,11 @@ def find_asset(logical_path)
         asset_full_path = ::Rails.root.join("public", @manifest.dir, asset_path)
         File.read(asset_full_path)
       end
+
+      # sprockets-rails < 2.2.2 does not have `application.assets_manifest=`
+      def self.compatible?
+        ::Rails.application.respond_to?(:assets_manifest)
+      end
     end
   end
 end

lib/react/server_rendering/sprockets_renderer.rb

@@ -61,16 +61,18 @@ class << self
       def asset_container
         @asset_container ||= if self.class.asset_container_class.present?
           self.class.asset_container_class.new
-        elsif ::Rails.application.config.assets.compile
-          EnvironmentContainer.new
+        elsif assets_precompiled? && ManifestContainer.compatible?
+          ManifestContainer.new
+        elsif assets_precompiled? && YamlManifestContainer.compatible?
+          YamlManifestContainer.new
         else
-          if ::Rails::VERSION::MAJOR == 3
-            YamlManifestContainer.new
-          else
-            ManifestContainer.new
-          end
+          EnvironmentContainer.new
         end
       end
+
+      def assets_precompiled?
+        !::Rails.application.config.assets.compile
+      end
     end
   end
 end

lib/react/server_rendering/yaml_manifest_container.rb

@@ -14,6 +14,10 @@ def find_asset(logical_path)
         asset_full_path = ::Rails.root.join("public", "assets", asset_path)
         File.read(asset_full_path)
       end
+
+      def self.compatible?
+        ::Rails::VERSION::MAJOR == 3
+      end
     end
   end
 end

test/react/server_rendering/manifest_container_test.rb

@@ -1,8 +1,6 @@
 require "test_helper"
 
-# Rails 3.x doesn't have `application.assets_manifest=`
-# I don't think we have to support Rails 3 + Sprockets 3 anyways!
-if Rails::VERSION::MAJOR > 3
+if React::ServerRendering::ManifestContainer.compatible?
   class ManifestContainerTest < ActiveSupport::TestCase
     def setup
       precompile_assets

test/react/server_rendering/yaml_manifest_container_test.rb

@@ -1,6 +1,6 @@
 require "test_helper"
 
-if Rails::VERSION::MAJOR == 3
+if React::ServerRendering::YamlManifestContainer.compatible?
   class YamlManifestContainerTest < ActiveSupport::TestCase
     def setup
       precompile_assets
@@ -18,4 +18,3 @@ def test_find_asset_gets_asset_contents
     end
   end
 end
-

test/test_helper.rb

@@ -54,7 +54,7 @@ def precompile_assets
     Rake::Task['assets:precompile'].invoke
   end
 
-  if Rails::VERSION::MAJOR > 3
+  if Rails.application.respond_to?(:assets_manifest)
     # Make a new manifest since assets weren't compiled before
     config = Rails.application.config
     path = File.join(config.paths['public'].first, config.assets.prefix)