support turning off and on the configuration option for no_direct_assignment

lib/aasm/base.rb

@@ -27,11 +27,19 @@ module AASM
 
       configure :enum, nil
 
-      if @state_machine.config.no_direct_assignment
-        @klass.send(:define_method, "#{@state_machine.config.column}=") do |state_name|
-          raise AASM::NoDirectAssignmentError.new('direct assignment of AASM column has been disabled (see AASM configuration for this class)')
+      # make sure to raise an error if no_direct_assignment is enabled
+      # and attribute is directly assigned though
+      @klass.class_eval %Q(
+        def #{@state_machine.config.column}=(state_name)
+          if self.class.aasm.state_machine.config.no_direct_assignment
+            raise AASM::NoDirectAssignmentError.new(
+              'direct assignment of AASM column has been disabled (see AASM configuration for this class)'
+            )
+          else
+            super
+          end
         end
-      end
+      )
     end
 
     # This method is both a getter and a setter

spec/models/active_record/localizer_test_model.rb

@@ -1,8 +1,6 @@
 class LocalizerTestModel < ActiveRecord::Base
   include AASM
 
-  attr_accessor :aasm_state
-
   aasm do
     state :opened, :initial => true
     state :closed

spec/unit/persistence/active_record_persistence_spec.rb

@@ -321,6 +321,24 @@ describe "direct assignment" do
     expect {obj.aasm_state = :running}.to raise_error(AASM::NoDirectAssignmentError)
     expect(obj.aasm_state.to_sym).to eql :pending
   end
+
+  it 'can be turned off and on again' do
+    obj = NoDirectAssignment.create
+    expect(obj.aasm_state.to_sym).to eql :pending
+
+    expect {obj.aasm_state = :running}.to raise_error(AASM::NoDirectAssignmentError)
+    expect(obj.aasm_state.to_sym).to eql :pending
+
+    # allow it temporarily
+    NoDirectAssignment.aasm.state_machine.config.no_direct_assignment = false
+    obj.aasm_state = :pending
+    expect(obj.aasm_state.to_sym).to eql :pending
+
+    # and forbid it again
+    NoDirectAssignment.aasm.state_machine.config.no_direct_assignment = true
+    expect {obj.aasm_state = :running}.to raise_error(AASM::NoDirectAssignmentError)
+    expect(obj.aasm_state.to_sym).to eql :pending
+  end
 end # direct assignment
 
 describe 'initial states' do