Prepend timestamps with namespace to avoid naming conflicts

lib/aasm/base.rb

@@ -268,7 +268,9 @@ def setup_timestamps(aasm_name)
 
       after_all_transitions do
         if self.class.aasm(:"#{aasm_name}").state_machine.config.timestamps
-          ts_setter = "#{aasm(aasm_name).to_state}_at="
+          namespace = self.class.aasm(:"#{aasm_name}").state_machine.config.namespace
+          base_setter = "#{aasm(aasm_name).to_state}_at="
+          ts_setter = !!namespace ? "#{namespace}_#{base_setter}" : base_setter
           respond_to?(ts_setter) && send(ts_setter, ::Time.now)
         end
       end

spec/models/timestamps_with_namespace_machine_example.rb

@@ -0,0 +1,13 @@
+class TimestampsWithNamespaceMachineExample
+  include AASM
+
+  attr_accessor :new_opened_at
+
+  aasm :my_state, timestamps: true, namespace: :new do
+    state :opened
+
+    event :open do
+      transitions to: :opened
+    end
+  end
+end

spec/unit/timestamps_spec.rb

@@ -29,4 +29,9 @@
     object = TimestampsWithNamedMachineExample.new
     expect { object.open }.to change { object.opened_at }.from(nil).to(instance_of(::Time))
   end
+
+  it 'calls a timestamp setter based on the state name and namespace when entering a new state using a namespace state machine' do
+    object = TimestampsWithNamespaceMachineExample.new
+    expect { object.open }.to change { object.new_opened_at }.from(nil).to(instance_of(::Time))
+  end
 end