Fix #7164. Property facets with a restriction in the baseName would incorrectly test null values.

Our tests missed this detail. The previous test also did
should_purge=True by default which doesn't property test for nullness.

src/ifctester/ifctester/facet.py

@@ -688,7 +688,9 @@ class Property(Facet):
                     elif prop is not None and prop != "":
                         props[pset_name][self.baseName] = prop
                 else:
-                    props[pset_name] = {k: v for k, v in pset_props.items() if k == self.baseName}
+                    props[pset_name] = {
+                        k: v for k, v in pset_props.items() if k == self.baseName and v is not None and v != ""
+                    }
 
                 if not bool(props[pset_name]):
                     if self.cardinality == "optional":

src/ifctester/test/test_facet.py

@@ -921,8 +921,11 @@ class TestProperty:
         pset = ifcopenshell.api.pset.add_pset(ifc, product=element, name="Foo_Bar")
         ifcopenshell.api.pset.edit_pset(ifc, pset=pset, properties={"AnotherProperty": "AnotherValue"})
         run("Elements with a matching pset but no property also fail", facet=facet, inst=element, expected=False)
-        ifcopenshell.api.pset.edit_pset(ifc, pset=pset, properties={"AnotherProperty": None})
+        ifcopenshell.api.pset.edit_pset(ifc, pset=pset, properties={"Foo": None}, should_purge=False)
         run("Properties with a null value fail", facet=facet, inst=element, expected=False)
+        restriction = Restriction(options={"pattern": "Fo.*"})
+        facet = Property(propertySet="Foo_Bar", baseName=restriction, dataType="IFCLABEL")
+        run("Pattern matched properties with a null value fail", facet=facet, inst=element, expected=False)
         ifcopenshell.api.pset.edit_pset(ifc, pset=pset, properties={"Foo": "Bar"})
         run("A name check will match any property with any string value", facet=facet, inst=element, expected=True)