Track last actions and friendlier error reporting when something breaks

src/ifctester/ifctester/facet.py

@@ -72,6 +72,8 @@ class Facet:
     def __init__(self, *parameters):
         self.status = None
         self.failures: list[FacetFailure] = []
+        self.parameters = []
+        self.applicability_templates = []
         for i, name in enumerate(self.parameters):
             setattr(self, name.replace("@", ""), parameters[i])
 
@@ -101,8 +103,10 @@ class Facet:
         return self
 
     def filter(
-        self, ifc_file: ifcopenshell.file, elements: list[ifcopenshell.entity_instance]
+        self, ifc_file: ifcopenshell.file, elements: Optional[list[ifcopenshell.entity_instance]]
     ) -> list[ifcopenshell.entity_instance]:
+        if not elements:
+            return []
         return [e for e in elements if self(e)]
 
     def to_string(
@@ -133,6 +137,7 @@ class Facet:
                     total_replacements += 1
                 if total_replacements == total_variables:
                     return template
+        return "This facet cannot be interpreted"
 
     def to_ids_value(self, parameter: Union[str, Restriction, list]) -> dict[str, Any]:
         if isinstance(parameter, str):

src/ifctester/ifctester/ids.py

@@ -75,8 +75,8 @@ class Ids:
         milestone=None,
     ):
         # Not part of the IDS spec, but very useful in practice
-        self.filepath = None
-        self.filename = None
+        self.filepath: Optional[str] = None
+        self.filename: Optional[str] = None
 
         self.specifications: List[Specification] = []
         self.info = {}
@@ -300,6 +300,7 @@ class Specification:
             return "optional"
         elif self.maxOccurs == 0:
             return "prohibited"
+        return "required"  # Fallback
 
     def set_usage(self, usage: Cardinality) -> None:
         if usage == "optional":