chore(state) expose __none__ state

lib/src/state_machine.dart

@@ -120,7 +120,9 @@ class State extends Disposable implements Function {
     });
   }
 
-  State._none(StateMachine machine) : this._('__none__', machine);
+  static const _NONE_STATE_NAME = '__none__';
+
+  State._none(StateMachine machine) : this._(_NONE_STATE_NAME, machine);
 
   State._wildcard() : this._('__wildcard__', null, listenTo: false);
 
@@ -137,10 +139,32 @@ class State extends Disposable implements Function {
     return _machine.current == this;
   }
 
+  /// When starting the machine
+  /// by calling stm.start(initialState)
+  /// the initialState State receives an
+  /// onEnter event where the from state
+  /// is this stub one.
+  /// 
+  /// You can check that condition with:
+  /// 
+  /// initialState.onEnter((change) {
+  ///   if (!change.from.isNone) {
+  ///     // do something here
+  ///   }
+  /// })
+  /// 
+  /// to ignore this false initial event.
+  /// 
+  /// bool, true if this state is None,
+  /// false otherwise
+  bool get isNone {
+    return name == _NONE_STATE_NAME;
+  }
+
   @override
   String toString() {
     String name = this.name;
-    if (name == '__none__') {
+    if (isNone) {
       name = 'none - state machine has yet to start';
     }
     return 'State: $name (active: ${this()}, machine: ${_machine.name})';
@@ -164,10 +188,24 @@ class StateChange {
 
   StateChange._(State this.from, State this.to, this.payload);
 
+  /// StateChange can also occour
+  /// after stm.start(initialState)
+  /// To ignore these events you can check
+  /// this flag and eventually ignore it:
+  /// 
+  /// initialState.onEnter((change) {
+  ///   if (!change.isInitial) {
+  ///     // do something here
+  ///   }
+  /// })
+  bool get isInitial {
+    return this.from.isNone;
+  }
+
   @override
   String toString() {
     StringBuffer sb = StringBuffer();
-    String fromName = from.name == '__none__' ? '(none)' : from.name;
+    String fromName = from.isNone ? '(none)' : from.name;
     sb.writeln('StateChange: ${fromName} --> ${to.name}');
     if (payload != null) {
       sb.writeln('    payload: $payload');
@@ -247,6 +285,7 @@ class StateMachine extends Disposable {
     /// This allows an initial state transition to occur
     /// when the machine is started via [start].
     _current = State._none(this);
+
     manageDisposable(_current);
   }
 

test/state_machine_test.dart

@@ -32,6 +32,7 @@ void main() {
 
     test('should be in a dummy state until the machine has been started', () {
       expect(machine.current.name, equals('__none__'));
+      expect(machine.current.isNone, isTrue);
     });
 
     test('should throw if machine is started more than once', () {

test/state_test.dart

@@ -79,6 +79,7 @@ void main() {
 
     test('.toString() should explain what the __none__ state means', () {
       State noneState = machine.current;
+      expect(noneState.isNone, isTrue);
       String s = noneState.toString();
       expect(s, contains('machine has yet to start'));
       expect(s, isNot(contains('__none__')));