fix: Log may contain only the 'label' attr

Author: fgmacedo

statemachine/io/scxml/actions.py

@@ -268,9 +268,14 @@ def __init__(self, action: LogAction):
         self.action = action
 
     def __call__(self, *args, **kwargs):
-        value = _eval(self.action.expr, **kwargs)
+        value = _eval(self.action.expr, **kwargs) if self.action.expr else None
 
-        msg = f"{self.action.label}: {value!r}" if self.action.label else f"{value!r}"
+        if self.action.label and self.action.expr is not None:
+            msg = f"{self.action.label}: {value!r}"
+        elif self.action.label:
+            msg = f"{self.action.label}"
+        else:
+            msg = f"{value!r}"
         print(msg)
 
 

statemachine/io/scxml/parser.py

@@ -85,7 +85,7 @@ def parse_scxml(scxml_content: str) -> StateMachineDefinition:  # noqa: C901
 
     # If the initial states definition does not contain any first level state,
     # we find the first level states that are ancestor of the initial states
-    # and also set them as the initial states.
+    # and also set them as the initial states
     if not set(definition.states.keys()) & definition.initial_states:
         not_found = set(definition.initial_states)
         for state, parents in visit_states(definition.states.values(), []):
@@ -241,7 +241,7 @@ def parse_assign(element: ET.Element) -> AssignAction:
 
 def parse_log(element: ET.Element) -> LogAction:
     label = element.attrib.get("label")
-    expr = element.attrib["expr"]
+    expr = element.attrib.get("expr")
     return LogAction(label=label, expr=expr)
 
 

statemachine/io/scxml/schema.py

@@ -39,7 +39,7 @@ class AssignAction(Action):
 @dataclass
 class LogAction(Action):
     label: "str | None"
-    expr: str
+    expr: "str | None"
 
 
 @dataclass