Fixes incorrect permitted states

Permitted states now returns the correct states when an event has more than one transition, and if a transition uses a guard.

lib/aasm/instance_base.rb

@@ -35,11 +35,23 @@ module AASM
 
     def states(options={})
       if options[:permitted]
-        # ugliness level 1000
-        permitted_event_names = events(:permitted => true).map(&:name)
-        transitions = @instance.class.aasm(@name).state_machine.events.values_at(*permitted_event_names).compact.map {|e| e.transitions_from_state(current_state) }
-        tos = transitions.map {|t| t[0] ? t[0].to : nil}.flatten.compact.map(&:to_sym).uniq
-        @instance.class.aasm(@name).states.select {|s| tos.include?(s.name.to_sym)}
+        permitted_events = events(:permitted => true)
+
+        # An array of arrays. Each inner array represents the transitions that
+        # transition from the current state for an event
+        event_transitions = permitted_events.map {|e| e.transitions_from_state(current_state) }
+
+        # An array of symbols that are possible :to transition states
+        to_state_names = event_transitions.map do |transitions|
+          return nil if transitions.empty?
+
+          # Return the :to state of the first transition that is allowed or nil
+          transition = transitions.find { |t| t.allowed?(@instance) }
+          transition ? transition.to : nil
+        end.flatten.compact.uniq
+
+        # Select states that are in to_state_names
+        @instance.class.aasm(@name).states.select {|s| to_state_names.include?(s.name)}
       else
         @instance.class.aasm(@name).states
       end

spec/models/multi_transitioner.rb

@@ -0,0 +1,24 @@
+class MultiTransitioner
+  include AASM
+
+  attr_accessor :can_run
+
+  def initialize
+    @can_run = false
+  end
+
+  aasm do
+    state :sleeping, :initial => true
+    state :running
+    state :dancing
+
+    event :start do
+      transitions :from => :sleeping, :to => :running, guard: :runnable?
+      transitions :from => :sleeping, :to => :dancing
+    end
+  end
+
+  def runnable?
+    @can_run
+  end
+end

spec/unit/inspection_spec.rb

@@ -17,6 +17,7 @@ describe 'inspection for common cases' do
   context "instance level inspection" do
     let(:foo) { Foo.new }
     let(:two) { FooTwo.new }
+    let(:multi) { MultiTransitioner.new }
 
     it "delivers all states" do
       states = foo.aasm.states
@@ -37,11 +38,13 @@ describe 'inspection for common cases' do
       states = two.aasm.states
       expect(states).to include(:open)
       expect(states).to include(:closed)
+      expect(states).to include(:final)
       expect(states).to include(:foo)
 
       states = two.aasm.states(:permitted => true)
       expect(states).to include(:closed)
       expect(states).not_to include(:open)
+      expect(states).not_to include(:final)
 
       two.close
       expect(two.aasm.states(:permitted => true)).to be_empty
@@ -54,6 +57,18 @@ describe 'inspection for common cases' do
       foo.close
       expect(foo.aasm.events).to be_empty
     end
+
+    it "delivers permitted states when multiple transitions are defined" do
+      multi.can_run = false
+      states = multi.aasm.states(:permitted => true)
+      expect(states).to_not include(:running)
+      expect(states).to include(:dancing)
+
+      multi.can_run = true
+      states = multi.aasm.states(:permitted => true)
+      expect(states).to include(:running)
+      expect(states).to_not include(:dancing)
+    end
   end
 
   it 'should list states in the order they have been defined' do