add class methods to get last/next run timestamps for a worker

lib/sidetiq/schedulable.rb

@@ -12,12 +12,28 @@ module Sidetiq
   #     end
   module Schedulable
     module ClassMethods
+      def last_scheduled_occurrence
+        get_timestamp "last"
+      end
+
+      def next_scheduled_occurrence
+        get_timestamp "next"
+      end
+
       def tiq(&block) # :nodoc:
         clock = Sidetiq::Clock.instance
         clock.synchronize do
           clock.schedule_for(self).instance_eval(&block)
         end
       end
+
+    private
+
+      def get_timestamp key
+        Sidekiq.redis do |redis|
+          (redis.get("sidetiq:#{name}:#{key}") || -1).to_f
+        end
+      end
     end
 
     def self.included(klass) # :nodoc:
@@ -25,4 +41,3 @@ module Sidetiq
     end
   end
 end
-

test/test_worker.rb

@@ -0,0 +1,25 @@
+require_relative 'helper'
+
+class TestWorker < Sidetiq::TestCase
+  class FakeWorker
+    include Sidetiq::Schedulable
+  end
+
+  def test_timestamps_for_new_worker
+    assert FakeWorker.last_scheduled_occurrence == -1
+    assert FakeWorker.next_scheduled_occurrence == -1
+  end
+
+  def test_timestamps_for_existing_worker
+    last_run = (Time.now - 100).to_f
+    next_run = (Time.now + 100).to_f
+
+    Sidekiq.redis do |redis|
+      redis.set "sidetiq:TestWorker::FakeWorker:last", last_run
+      redis.set "sidetiq:TestWorker::FakeWorker:next", next_run
+    end
+
+    assert FakeWorker.last_scheduled_occurrence == last_run
+    assert FakeWorker.next_scheduled_occurrence == next_run
+  end
+end