Allow specifying recurring tasks just with a "command"

No need to have a class, can specify this using just a command for which
we'd provide a default RecurringtJob class that will just eval the command.

Author: rosa

app/jobs/solid_queue/recurring_job.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class SolidQueue::RecurringJob < ActiveJob::Base
+  queue_as :solid_queue_recurring
+
+  def perform(command)
+    eval(command)
+  end
+end

app/models/solid_queue/recurring_task.rb

@@ -7,10 +7,14 @@ class RecurringTask < Record
     serialize :arguments, coder: Arguments, default: []
 
     validate :supported_schedule
+    validate :ensure_command_or_class_present
     validate :existing_job_class
 
     scope :static, -> { where(static: true) }
 
+    mattr_accessor :default_job_class
+    self.default_job_class = RecurringJob
+
     class << self
       def wrap(args)
         args.is_a?(self) ? args : from_configuration(args.first, **args.second)
@@ -20,6 +24,7 @@ def from_configuration(key, **options)
         new \
           key: key,
           class_name: options[:class],
+          command: options[:command],
           arguments: options[:args],
           schedule: options[:schedule],
           queue_name: options[:queue].presence,
@@ -85,8 +90,14 @@ def supported_schedule
         end
       end
 
+      def ensure_command_or_class_present
+        unless command.present? || class_name.present?
+          errors.add :base, :command_and_class_blank, message: "either command or class_name must be present"
+        end
+      end
+
       def existing_job_class
-        unless job_class.present?
+        if class_name.present? && job_class.nil?
           errors.add :class_name, :undefined, message: "doesn't correspond to an existing class"
         end
       end
@@ -113,7 +124,9 @@ def perform_later
       end
 
       def arguments_with_kwargs
-        if arguments.last.is_a?(Hash)
+        if class_name.nil?
+          command
+        elsif arguments.last.is_a?(Hash)
           arguments[0...-1] + [ Hash.ruby2_keywords_hash(arguments.last) ]
         else
           arguments
@@ -126,7 +139,7 @@ def parsed_schedule
       end
 
       def job_class
-        @job_class ||= class_name&.safe_constantize
+        @job_class ||= class_name.present? ? class_name.safe_constantize : self.class.default_job_class
       end
 
       def enqueue_options

test/models/solid_queue/recurring_task_test.rb

@@ -122,11 +122,17 @@ def perform
     assert_not SolidQueue::RecurringTask.new(key: "task-id", class_name: "SolidQueue::RecurringTaskTest::JobWithoutArguments").valid?
   end
 
-  test "undefined job class" do
+  test "valid and invalid job class and command" do
+    # Command
+    assert recurring_task_with(command: "puts '¡hola!'").valid?
+    # Class
+    assert recurring_task_with(class_name: "JobWithPriority").valid?
+
+    # Invalid class name
     assert_not recurring_task_with(class_name: "UnknownJob").valid?
 
-    # Empty class name
-    assert_not SolidQueue::RecurringTask.new(key: "task-id", schedule: "every minute").valid?
+    # Empty class name and command
+    assert_not recurring_task_with(key: "task-id", schedule: "every minute").valid?
   end
 
   test "task with custom queue and priority" do
@@ -154,6 +160,13 @@ def perform
     assert_equal 4, job.priority
   end
 
+  test "task configured with a command" do
+    task = recurring_task_with(command: "JobBuffer.add('from_a_command')")
+    enqueue_and_assert_performed_with_result(task, "from_a_command")
+
+    assert_equal "SolidQueue::RecurringJob", SolidQueue::Job.last.class_name
+  end
+
   private
     def enqueue_and_assert_performed_with_result(task, result)
       assert_difference [ -> { SolidQueue::Job.count }, -> { SolidQueue::ReadyExecution.count } ], +1 do
@@ -170,7 +183,13 @@ def enqueue_and_assert_performed_with_result(task, result)
       assert_equal result, JobBuffer.last_value
     end
 
-    def recurring_task_with(class_name:, **options)
-      SolidQueue::RecurringTask.from_configuration("task-id", class: "SolidQueue::RecurringTaskTest::#{class_name}", **options.with_defaults(schedule: "every hour"))
+    def recurring_task_with(class_name: nil, **options)
+      options = options.dup.with_defaults(schedule: "every hour")
+
+      if class_name.present?
+        options[:class] = "SolidQueue::RecurringTaskTest::#{class_name}"
+      end
+
+      SolidQueue::RecurringTask.from_configuration("task-id", **options)
     end
 end

test/unit/scheduler_test.rb

@@ -17,7 +17,7 @@ class SchedulerTest < ActiveSupport::TestCase
     scheduler.stop
   end
 
-  test "run more than one instance of the dispatcher with recurring tasks" do
+  test "run more than one instance of the scheduler with recurring tasks" do
     recurring_tasks = { example_task: { class: "AddToBufferJob", schedule: "every second", args: 42 } }
     schedulers = 2.times.collect do
       SolidQueue::Scheduler.new(recurring_tasks: recurring_tasks)