Adds Rails:Command for dev:cache that has the same behaviour as the rake task

railties/lib/rails/commands/dev/dev_command.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+require "rails/dev_caching"
+
+module Rails
+  module Command
+    class DevCommand < Base # :nodoc:
+      desc "Toggle development mode caching on/off"
+      def cache
+        Rails::DevCaching.enable_by_file
+      end
+    end
+  end
+end

railties/test/commands/dev_test.rb

@@ -0,0 +1,65 @@
+# frozen_string_literal: true
+
+require "isolation/abstract_unit"
+require "rails/command"
+
+class Rails::Command::DevTest < ActiveSupport::TestCase
+  setup :build_app
+  teardown :teardown_app
+
+  test "`rails dev:cache` creates both caching and restart file when restart file doesn't exist and dev caching is currently off" do
+    Dir.chdir(app_path) do
+      assert_not File.exist?("tmp/caching-dev.txt")
+      assert_not File.exist?("tmp/restart.txt")
+
+      assert_equal <<~OUTPUT, run_dev_cache_command
+        Development mode is now being cached.
+      OUTPUT
+
+      assert File.exist?("tmp/caching-dev.txt")
+      assert File.exist?("tmp/restart.txt")
+    end
+  end
+
+  test "`rails dev:cache` creates caching file and touches restart file when dev caching is currently off" do
+    Dir.chdir(app_path) do
+      app_file("tmp/restart.txt", "")
+
+      assert_not File.exist?("tmp/caching-dev.txt")
+      assert File.exist?("tmp/restart.txt")
+      restart_file_time_before = File.mtime("tmp/restart.txt")
+
+      assert_equal <<~OUTPUT, run_dev_cache_command
+        Development mode is now being cached.
+      OUTPUT
+
+      assert File.exist?("tmp/caching-dev.txt")
+      restart_file_time_after = File.mtime("tmp/restart.txt")
+      assert_operator restart_file_time_before, :<, restart_file_time_after
+    end
+  end
+
+  test "`rails dev:cache` removes caching file and touches restart file when dev caching is currently on" do
+    Dir.chdir(app_path) do
+      app_file("tmp/caching-dev.txt", "")
+      app_file("tmp/restart.txt", "")
+
+      assert File.exist?("tmp/caching-dev.txt")
+      assert File.exist?("tmp/restart.txt")
+      restart_file_time_before = File.mtime("tmp/restart.txt")
+
+      assert_equal <<~OUTPUT, run_dev_cache_command
+        Development mode is no longer being cached.
+      OUTPUT
+
+      assert_not File.exist?("tmp/caching-dev.txt")
+      restart_file_time_after = File.mtime("tmp/restart.txt")
+      assert_operator restart_file_time_before, :<, restart_file_time_after
+    end
+  end
+
+  private
+    def run_dev_cache_command
+      rails "dev:cache"
+    end
+end