Fix github issue jakesgordon#17 - Don't swallow errors in SM callbacks

jakesgordon · jakesgordon · commit 38a8f2b040fa · 2012-02-12T09:07:06.000-08:00
Default behavior for `fsm.error` handler is to rethrow original exception (if there is one). Caller can still customize however they see fit.
diff --git a/state-machine.js b/state-machine.js
@@ -63,7 +63,7 @@
       fsm.is      = function(state) { return this.current == state; };
       fsm.can     = function(event) { return !this.transition && (map[event].hasOwnProperty(this.current) || map[event].hasOwnProperty(StateMachine.WILDCARD)); }
       fsm.cannot  = function(event) { return !this.can(event); };
-      fsm.error   = cfg.error || function(name, from, to, args, error, msg) { throw msg; }; // default behavior when something unexpected happens is to throw an exception, but caller can override this behavior if desired (see github issue #3)
+      fsm.error   = cfg.error || function(name, from, to, args, error, msg, e) { throw e || msg; }; // default behavior when something unexpected happens is to throw an exception, but caller can override this behavior if desired (see github issue #3 and #17)
 
       if (initial && !initial.defer)
         fsm[initial.event]();
@@ -80,7 +80,7 @@
           return func.apply(fsm, [name, from, to].concat(args));
         }
         catch(e) {
-          return fsm.error(name, from, to, args, StateMachine.Error.INVALID_CALLBACK, "an exception occurred in a caller-provided callback function");
+          return fsm.error(name, from, to, args, StateMachine.Error.INVALID_CALLBACK, "an exception occurred in a caller-provided callback function", e);
         }
       }
     },
diff --git a/state-machine.min.js b/state-machine.min.js
diff --git a/test/test_basics.js b/test/test_basics.js
@@ -151,7 +151,7 @@ test("inappropriate events", function() {
 test("inappropriate event handling can be customized", function() {
 
   var fsm = StateMachine.create({
-    error: function(e, name, from, to, args, msg) { return msg; }, // return error message instead of throwing an exception
+    error: function(name, from, to, args, error, msg) { return msg; }, // return error message instead of throwing an exception
     initial: 'green',
     events: [
       { name: 'warn',  from: 'green',  to: 'yellow' },
@@ -363,6 +363,26 @@ test("callback arguments are correct", function() {
 
 //-----------------------------------------------------------------------------
 
+test("exceptions in caller-provided callbacks are not swallowed (github issue #17)", function() {
+
+  var fsm = StateMachine.create({
+    initial: 'green',
+    events: [
+      { name: 'warn',  from: 'green',  to: 'yellow' },
+      { name: 'panic', from: 'yellow', to: 'red'    },
+      { name: 'calm',  from: 'red',    to: 'yellow' }
+    ],
+    callbacks: {
+      onenteryellow: function() { throw 'oops'; }
+    }});
+
+    equals(fsm.current, 'green', "initial state should be green");
+
+    raises(fsm.warn.bind(fsm), /oops/);
+});
+
+//-----------------------------------------------------------------------------
+
 test("no-op transitions (github issue #5)", function() {
 
   var fsm = StateMachine.create({

Original file line number	Diff line number	Diff line change
`@@ -63,7 +63,7 @@`
`63`	`63`	`fsm.is = function(state) { return this.current == state; };`
`64`	`64`	`fsm.can = function(event) { return !this.transition && (map[event].hasOwnProperty(this.current) \|\| map[event].hasOwnProperty(StateMachine.WILDCARD)); }`
`65`	`65`	`fsm.cannot = function(event) { return !this.can(event); };`
`66`		`- fsm.error = cfg.error \|\| function(name, from, to, args, error, msg) { throw msg; }; // default behavior when something unexpected happens is to throw an exception, but caller can override this behavior if desired (see github issue #3)`
	`66`	`+ fsm.error = cfg.error \|\| function(name, from, to, args, error, msg, e) { throw e \|\| msg; }; // default behavior when something unexpected happens is to throw an exception, but caller can override this behavior if desired (see github issue #3 and #17)`
`67`	`67`
`68`	`68`	`if (initial && !initial.defer)`
`69`	`69`	`fsm[initial.event]();`
`@@ -80,7 +80,7 @@`
`80`	`80`	`return func.apply(fsm, [name, from, to].concat(args));`
`81`	`81`	`}`
`82`	`82`	`catch(e) {`
`83`		`- return fsm.error(name, from, to, args, StateMachine.Error.INVALID_CALLBACK, "an exception occurred in a caller-provided callback function");`
	`83`	`+ return fsm.error(name, from, to, args, StateMachine.Error.INVALID_CALLBACK, "an exception occurred in a caller-provided callback function", e);`
`84`	`84`	`}`
`85`	`85`	`}`
`86`	`86`	`},`