Add rake dev:cache task to enable dev mode caching.

Taken from @Sonopa's commits on PR #19091.

Add support for dev caching via "rails s" flags.

Implement suggestions from @kaspth.

Remove temporary cache file if server does not have flags.

Break at 80 characters in railties/CHANGELOG.md

Remove ability to disable cache based on server options.

Add more comprehensive options: --dev-caching / --no-dev-caching

1 files changed, 35 insertions, 0 deletions

diff --git a/railties/test/application/rake/dev_test.rb b/railties/test/application/rake/dev_test.rb
new file mode 100644
index 0000000000..28d8b22a37
--- /dev/null
+++ b/railties/test/application/rake/dev_test.rb
@@ -0,0 +1,35 @@
+require 'isolation/abstract_unit'
+
+module ApplicationTests
+  module RakeTests
+    class RakeDevTest < ActiveSupport::TestCase
+      include ActiveSupport::Testing::Isolation
+
+      def setup
+        build_app
+        boot_rails
+      end
+
+      def teardown
+        teardown_app
+      end
+
+      test 'dev:cache creates file and outputs message' do
+        Dir.chdir(app_path) do
+          output = `rake dev:cache`
+          assert File.exist?('tmp/caching-dev.txt')
+          assert_match(/Development mode is now being cached/, output)
+        end
+      end
+
+      test 'dev:cache deletes file and outputs message' do
+        Dir.chdir(app_path) do
+          output = `rake dev:cache`        
+          output = `rake dev:cache`
+          assert_not File.exist?('tmp/caching-dev.txt')
+          assert_match(/Development mode is no longer being cached/, output)
+        end
+      end
+    end
+  end
+end