Always initialize assets environment in rake task

lib/sprockets/rails/task.rb

@@ -16,7 +16,9 @@ def initialize(app = nil)
 
       def environment
         if app
-          app.assets
+          # Use initialized app.assets or force build an environment if
+          # config.assets.compile is disabled
+          app.assets || Sprockets::Railtie.build_environment(app)
         else
           super
         end

lib/sprockets/railtie.rb

@@ -69,7 +69,12 @@ def configure(&block)
       Sprockets::Rails::Task.new(app)
     end
 
-    def self.build_environment(app)
+    def build_environment(app, initialized = nil)
+      initialized = app.initialized? if initialized.nil?
+      unless initialized
+        ::Rails.logger.warn "Application uninitialized: Try calling YourApp::Application.initialize!"
+      end
+
       config = app.config
       env = Sprockets::Environment.new(app.root.to_s)
 
@@ -126,7 +131,7 @@ def self.build_manifest(app)
       config = app.config
 
       if config.assets.compile
-        app.assets = self.build_environment(app)
+        app.assets = self.build_environment(app, true)
         app.routes.prepend do
           mount app.assets => config.assets.prefix
         end

test/test_railtie.rb

@@ -1,9 +1,17 @@
-require 'minitest/autorun'
 require 'active_support'
 require 'active_support/testing/isolation'
+require 'minitest/autorun'
 
 Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)
 
+def silence_stderr
+  orig_stderr = $stderr.clone
+  $stderr.reopen File.new('/dev/null', 'w')
+  yield
+ensure
+  $stderr.reopen orig_stderr
+end
+
 class TestBoot < Minitest::Test
   include ActiveSupport::Testing::Isolation
 
@@ -264,4 +272,82 @@ def test_manifest_path_respects_rails_public_path
     assert_match %r{test_public/assets/manifest-.*\.json$}, manifest.path
     assert_match %r{test_public/assets$}, manifest.dir
   end
+
+  def test_load_tasks
+    app.initialize!
+    app.load_tasks
+
+    assert Rake.application['assets:environment']
+    assert Rake.application['assets:precompile']
+    assert Rake.application['assets:clean']
+    assert Rake.application['assets:clobber']
+  end
+
+  def test_task_precompile
+    app.configure do
+      config.assets.paths << FIXTURES_PATH
+      config.assets.precompile += ["foo.js"]
+    end
+    app.initialize!
+    app.load_tasks
+
+    path = "#{app.assets_manifest.dir}/foo-4ef5541f349f7ed5a0d6b71f2fa4c82745ca106ae02f212aea5129726ac6f6ab.js"
+
+    silence_stderr do
+      Rake.application['assets:clobber'].execute
+    end
+    refute File.exist?(path)
+
+    silence_stderr do
+      Rake.application['assets:precompile'].execute
+    end
+    assert File.exist?(path)
+
+    silence_stderr do
+      Rake.application['assets:clobber'].execute
+    end
+    refute File.exist?(path)
+  end
+
+  def test_task_precompile_compile_false
+    app.configure do
+      config.assets.compile = false
+      config.assets.paths << FIXTURES_PATH
+      config.assets.precompile += ["foo.js"]
+    end
+    app.initialize!
+    app.load_tasks
+
+    path = "#{app.assets_manifest.dir}/foo-4ef5541f349f7ed5a0d6b71f2fa4c82745ca106ae02f212aea5129726ac6f6ab.js"
+
+    silence_stderr do
+      Rake.application['assets:clobber'].execute
+    end
+    refute File.exist?(path)
+
+    silence_stderr do
+      Rake.application['assets:precompile'].execute
+    end
+    assert File.exist?(path)
+
+    silence_stderr do
+      Rake.application['assets:clobber'].execute
+    end
+    refute File.exist?(path)
+  end
+
+  def test_direct_build_environment_call
+    app.configure do
+      config.assets.paths << "javascripts"
+      config.assets.paths << "stylesheets"
+    end
+    app.initialize!
+
+    assert env = Sprockets::Railtie.build_environment(app)
+    assert_kind_of Sprockets::Environment, env
+
+    assert_equal ROOT, env.root
+    assert_equal ["#{ROOT}/javascripts", "#{ROOT}/stylesheets"],
+      env.paths.sort
+  end
 end