Allow no-op transition event if 'to' parameter is not specified (github issue jakesgordon#5)

  jakesgordon#5

Author: jakesgordon

state-machine.js

@@ -26,7 +26,7 @@ StateMachine = {
       var from = (e.from instanceof Array) ? e.from : [e.from];
       map[e.name] = map[e.name] || {};
       for (var n = 0 ; n < from.length ; n++)
-        map[e.name][from[n]] = e.to;
+        map[e.name][from[n]] = e.to || from[n]; // allow no-op transition if 'to' is not specified
     };
 
     if (initial) {

state-machine.min.js

@@ -18,7 +18,7 @@ test("multiple 'from' states for the same event", function() {
   equals(fsm.current, 'green', "initial state should be green");
 
   ok(fsm.can('warn'),     "should be able to warn from green state")
-  ok(fsm.can('panic'),    "should NOT be able to panic from green state")
+  ok(fsm.can('panic'),    "should be able to panic from green state")
   ok(fsm.cannot('calm'),  "should NOT be able to calm from green state")
   ok(fsm.cannot('clear'), "should NOT be able to clear from green state")
 
@@ -66,6 +66,48 @@ test("multiple 'to' states for the same event", function() {
 
 //-----------------------------------------------------------------------------
 
+test("no-op transitions (github issue #5) with multiple from states", function() {
+
+  var fsm = StateMachine.create({
+    initial: 'green',
+    events: [
+      { name: 'warn',  from: 'green',             to: 'yellow' },
+      { name: 'panic', from: ['green', 'yellow'], to: 'red'    },
+      { name: 'noop',  from: ['green', 'yellow']               }, // NOTE: 'to' not specified
+      { name: 'calm',  from: 'red',               to: 'yellow' },
+      { name: 'clear', from: ['yellow', 'red'],   to: 'green'  },
+  ]});
+
+  equals(fsm.current, 'green', "initial state should be green");
+
+  ok(fsm.can('warn'),     "should be able to warn from green state")
+  ok(fsm.can('panic'),    "should be able to panic from green state")
+  ok(fsm.can('noop'),     "should be able to noop from green state")
+  ok(fsm.cannot('calm'),  "should NOT be able to calm from green state")
+  ok(fsm.cannot('clear'), "should NOT be able to clear from green state")
+
+  fsm.noop();  equals(fsm.current, 'green',  "noop  event should not transition");
+  fsm.warn();  equals(fsm.current, 'yellow', "warn  event should transition from green  to yellow");
+
+  ok(fsm.cannot('warn'),  "should NOT be able to warn  from yellow state")
+  ok(fsm.can('panic'),    "should     be able to panic from yellow state")
+  ok(fsm.can('noop'),     "should     be able to noop  from yellow state")
+  ok(fsm.cannot('calm'),  "should NOT be able to calm  from yellow state")
+  ok(fsm.can('clear'),    "should     be able to clear from yellow state")
+
+  fsm.noop();  equals(fsm.current, 'yellow', "noop  event should not transition");
+  fsm.panic(); equals(fsm.current, 'red',    "panic event should transition from yellow to red");
+
+  ok(fsm.cannot('warn'),  "should NOT be able to warn  from red state")
+  ok(fsm.cannot('panic'), "should NOT be able to panic from red state")
+  ok(fsm.cannot('noop'),  "should NOT be able to noop  from red state")
+  ok(fsm.can('calm'),     "should     be able to calm  from red state")
+  ok(fsm.can('clear'),    "should     be able to clear from red state")
+
+});
+
+//-----------------------------------------------------------------------------
+
 test("callbacks are called when appropriate for multiple 'from' and 'to' transitions", function() {
 
   var called = [];

test/test_advanced.js

@@ -361,3 +361,31 @@ test("callback arguments are correct", function() {
 
 });
 
+//-----------------------------------------------------------------------------
+
+test("no-op transitions (github issue #5)", function() {
+
+  var fsm = StateMachine.create({
+    initial: 'green',
+    events: [
+      { name: 'noop',  from: 'green',               }, // NOTE: no 'to' option specified
+      { name: 'warn',  from: 'green',  to: 'yellow' },
+      { name: 'panic', from: 'yellow', to: 'red'    },
+      { name: 'calm',  from: 'red',    to: 'yellow' },
+      { name: 'clear', from: 'yellow', to: 'green'  }
+  ]});
+
+  equals(fsm.current, 'green', "initial state should be green");
+
+  ok(fsm.can('noop'), "should be able to noop from green state")
+  ok(fsm.can('warn'), "should be able to warn from green state")
+
+  fsm.noop(); equals(fsm.current, 'green',  "noop event should not cause a transition (there is no 'to' specified)");
+  fsm.warn(); equals(fsm.current, 'yellow', "warn event should transition from green to yellow");
+
+  ok(fsm.cannot('noop'), "should NOT be able to noop from yellow state")
+  ok(fsm.cannot('warn'), "should NOT be able to warn from yellow state")
+  
+});
+
+