fix error if uses transition callback without transitions map

README.md

@@ -11,7 +11,7 @@ You can visualize transitions map with [enum_machine-contrib](https://github.com
 - namespaced (via attr) by default: `order.state.to_collected`
 - [aliases](Aliases)
 - guarantees of existing transitions
-- simple run transitions with callbacks `order.update(state: "collected")` or `order.to_collected`
+- simple run transitions with callbacks `order.update(state: "collected")` or `order.state.to_collected`
 - `aasm` / `state_machines` **event driven**, `enum_machine` **state driven**
 
 ```ruby
@@ -103,8 +103,9 @@ product.state.forming? # => true
 class Product < ActiveRecord::Base
   enum_machine :color, %w[red green blue]
   enum_machine :state, %w[created approved cancelled activated] do
+    # transitions(any => any) - allow all transitions
     transitions(
-      nil                    => "red",
+      nil                    => "created",
       "created"              => [nil, "approved"],
       %w[cancelled approved] => "activated",
       "activated"            => %w[created cancelled],
@@ -133,6 +134,24 @@ product.state.to_activated! # => EnumMachine::Error: transition "created" => "ac
 product.state.to_approved! # => true; equal to `product.update!(state: "approve")`
 ```
 
+#### Skip transitions
+```ruby
+product = Product.new(state: "created")
+product.skip_state_transitions { product.save }
+```
+
+method generated as `skip_#{enum_name}_transitions`
+
+#### Skip in factories
+```ruby
+FactoryBot.define do
+  factory :product do
+    name { Faker::Commerce.product_name }
+    to_create { |product| product.skip_state_transitions { product.save! } }
+  end
+end
+```
+
 ### I18n
 
 **ru.yml**

lib/enum_machine.rb

@@ -19,8 +19,12 @@ class InvalidTransition < Error
     def initialize(machine, from, to)
       @from = from
       @to = to
-      @enum_const = machine.base_klass.const_get(machine.enum_const_name)
-      super("Transition #{from.inspect} => #{to.inspect} not defined in enum_machine #{enum_const.name}")
+      @enum_const =
+        begin
+          machine.base_klass.const_get(machine.enum_const_name)
+        rescue NameError # rubocop:disable Lint/SuppressedException
+        end
+      super("Transition #{from.inspect} => #{to.inspect} not defined in enum_machine :#{machine.attr_name}")
     end
 
   end

lib/enum_machine/driver_active_record.rb

@@ -9,7 +9,7 @@ def enum_machine(attr, enum_values, i18n_scope: nil, &block)
       i18n_scope ||= "#{klass.base_class.to_s.underscore}.#{attr}"
 
       enum_const_name = attr.to_s.upcase
-      machine = Machine.new(enum_values, klass, enum_const_name)
+      machine = Machine.new(enum_values, klass, enum_const_name, attr)
       machine.instance_eval(&block) if block
 
       enum_klass = BuildClass.call(enum_values: enum_values, i18n_scope: i18n_scope, machine: machine)

lib/enum_machine/machine.rb

@@ -3,12 +3,13 @@
 module EnumMachine
   class Machine
 
-    attr_reader :enum_values, :base_klass, :enum_const_name
+    attr_reader :enum_values, :base_klass, :enum_const_name, :attr_name
 
-    def initialize(enum_values, base_klass = nil, enum_const_name = nil) # rubocop:disable Gp/OptArgParameters
+    def initialize(enum_values, base_klass = nil, enum_const_name = nil, attr_name = nil) # rubocop:disable Gp/OptArgParameters
       @enum_values = enum_values
       @base_klass = base_klass
       @enum_const_name = enum_const_name
+      @attr_name = attr_name
       @transitions = {}
       @before_transition = {}
       @after_transition = {}

spec/enum_machine/active_record_machine_spec.rb

@@ -168,6 +168,19 @@ def a
     expect { m.update!(color: "green") }.to change(m, :message).to "green => green"
   end
 
+  it "check error when empty transition" do
+    expect {
+      Class.new(TestModel) do
+        enum_machine :state, %w[picked completed] do
+          after_transition(nil => "picked") { 1 }
+        end
+      end
+    }.to raise_error(EnumMachine::InvalidTransition) { |e|
+      expect(e.from).to be_nil
+      expect(e.message).to include('Transition nil => "picked" not defined in enum_machine')
+    }
+  end
+
   it "dup AR object not linked with original" do
     m = model.create(state: "created", color: "green")
     m.state # init parent