Provide a working example for #63 Recommendation for undoing an event

test/advanced_examples_test.rb

@@ -0,0 +1,61 @@
+require File.join(File.dirname(__FILE__), 'test_helper')
+require 'workflow'
+class AdvanceExamplesTest < ActiveRecordTestCase
+
+  class Article
+    include Workflow
+    workflow do
+      state :new do
+        event :submit, :transitions_to => :awaiting_review
+      end
+      state :awaiting_review do
+        event :review, :transitions_to => :being_reviewed
+      end
+      state :being_reviewed do
+        event :accept, :transitions_to => :accepted
+        event :reject, :transitions_to => :rejected
+      end
+      state :accepted do
+      end
+      state :rejected do
+      end
+    end
+  end
+
+  test '#63 undoing event - automatically add revert events for every defined event' do
+    # also see https://github.com/geekq/workflow/issues/63
+    spec = Article.workflow_spec
+    spec.state_names.each do |state_name|
+      state = spec.states[state_name]
+
+        (state.events.values.reject {|e| e.name.to_s =~ /^revert_/ }).each do |event|
+          event_name = event.name
+          revert_event_name = "revert_" + event_name.to_s
+
+          # Add revert events
+          spec.states[event.transitions_to.to_sym].events[revert_event_name.to_sym] =
+            Workflow::Event.new(revert_event_name, state, {})
+
+          # Add methods for revert events
+          Article.module_eval do
+            define_method "#{revert_event_name}!".to_sym do |*args|
+              process_event!(revert_event_name, *args)
+            end
+            define_method "can_#{revert_event_name}?" do
+              return self.current_state.events.include?(revert_event_name)
+            end
+          end
+
+        end
+    end
+
+    a = Article.new
+    assert(a.new?, "should start with the 'new' state")
+    a.submit!
+    assert(a.awaiting_review?, "should now be in 'awaiting_review' state")
+    assert_equal(['revert_submit', 'review'], a.current_state.events.keys.map(&:to_s).sort)
+    a.revert_submit! # this method is added by our meta programming magic above
+    assert(a.new?, "should now be back in the 'new' state")
+  end
+
+end