Deprecate support of older `config.ru`

Since Rails 4.0, `config.ru` generated by default uses instances of
`Rails.application`.  Therefore, I think that it is good to deprecate
the old behavior.

Related: #9669

1 files changed, 31 insertions, 0 deletions

diff --git a/railties/test/application/server_test.rb b/railties/test/application/server_test.rb
new file mode 100644
index 0000000000..07880a5025
--- /dev/null
+++ b/railties/test/application/server_test.rb
@@ -0,0 +1,31 @@
+require "isolation/abstract_unit"
+require "rails/command"
+require "rails/commands/server/server_command"
+
+module ApplicationTests
+  class ServerTest < ActiveSupport::TestCase
+    include ActiveSupport::Testing::Isolation
+
+    def setup
+      build_app
+    end
+
+    def teardown
+      teardown_app
+    end
+
+    test "deprecate support of older `config.ru`" do
+      remove_file "config.ru"
+      app_file "config.ru", <<-RUBY
+        require_relative 'config/environment'
+        run AppTemplate::Application
+      RUBY
+
+      server = Rails::Server.new(config: "#{app_path}/config.ru")
+      server.app
+
+      log = File.read(Rails.application.config.paths["log"].first)
+      assert_match(/DEPRECATION WARNING: Use `Rails::Application` subclass to start the server is deprecated/, log)
+    end
+  end
+end