Clarify usage of --arguments in CLI

README.md

@@ -277,10 +277,10 @@ $ bundle exec maintenance_tasks perform Maintenance::ImportPostsTask --csv 'path
 ```
 
 To run a Task that takes arguments from the command line, use the --arguments
-option, ensuring that the argument value is passed as a string:
+option, passing arguments as a set of <key>:<value> pairs:
 
 ```bash
-$ bundle exec maintenance_tasks perform Maintenance::ParamsTask --arguments=post_ids:"1,2,3"
+$ bundle exec maintenance_tasks perform Maintenance::ParamsTask --arguments post_ids:1,2,3 content:"Hello, World!"
 ```
 
 You can also run a Task in Ruby by sending `run` with a Task name to Runner:

app/controllers/maintenance_tasks/tasks_controller.rb

@@ -28,7 +28,7 @@ def run
       task = Runner.run(
         name: params.fetch(:id),
         csv_file: params[:csv_file],
-        arguments: task_arguments.to_h,
+        arguments: params.fetch(:task_arguments, {}).permit!.to_h,
       )
       redirect_to(task_path(task))
     rescue ActiveRecord::RecordInvalid => error
@@ -42,11 +42,6 @@ def run
 
     private
 
-    def task_arguments
-      return {} unless params[:task_arguments].present?
-      params.require(:task_arguments).permit!
-    end
-
     def set_refresh
       @refresh = 3
     end

app/models/maintenance_tasks/run.rb

@@ -279,10 +279,9 @@ def arguments_match_task_attributes
       invalid_argument_keys = arguments.keys - task.attribute_names
       if invalid_argument_keys.any?
         error_message = <<~MSG.squish
-          used not specified as parameters on Task:
-          #{invalid_argument_keys.join(", ")}
+          Unknown parameters: #{invalid_argument_keys.map(&:to_sym).join(", ")}
         MSG
-        errors.add(:arguments, error_message)
+        errors.add(:base, error_message)
       end
     end
   end

lib/maintenance_tasks/cli.rb

@@ -30,8 +30,7 @@ def exit_on_failure?
 
     # Specify arguments to supply to a Task supporting parameters
     option :arguments, type: :hash, desc: "Supply arguments for a Task that "\
-      "accepts parameters as a set of key-value pairs. Ensure that argument
-      values are provided as strings."
+      "accepts parameters as a set of <key>:<value> pairs."
 
     # Command to run a Task.
     #

test/models/maintenance_tasks/run_test.rb

@@ -35,7 +35,7 @@ class RunTest < ActiveSupport::TestCase
       )
       refute_predicate run, :valid?
       assert_equal run.errors.full_messages.first,
-        "Arguments used not specified as parameters on Task: bad_argument"
+        "Unknown parameters: bad_argument"
     end
 
     test "invalid if arguments are supplied but Task does not support parameters" do
@@ -45,7 +45,7 @@ class RunTest < ActiveSupport::TestCase
       )
       refute_predicate run, :valid?
       assert_equal run.errors.full_messages.first,
-        "Arguments used not specified as parameters on Task: post_ids"
+        "Unknown parameters: post_ids"
     end
 
     test "#persist_progress persists increments to tick count and time_running" do