Add 'is set' predicate and not empty check

- Introduced a new predicate for checking if a parameter is set.
- Added a method to verify if a parameter exists and isn't empty.
- Updated tests to cover the new 'not empty' functionality.

src/predicates.py

@@ -17,4 +17,5 @@ PREDICATE_METHOD_MAP = {
     "identical to": PropertyRules.is_identical_value.__name__,
     "contains": PropertyRules.is_parameter_value_containing.__name__,
     "does not contain": PropertyRules.is_parameter_value_not_containing.__name__,
+    "is set": PropertyRules.is_parameter_value_not_empty.__name__,
 }

src/rules.py

@@ -890,3 +890,35 @@ class PropertyRules:
         return PropertyRules.compare_values(
             parameter_value, value_to_match, case_sensitive=True, tolerance=0, allow_yes_no_bools=False, use_exact=True
         )
+
+    @staticmethod
+    def is_parameter_value_not_empty(speckle_object: Base, parameter_name: str) -> bool:
+        """Checks if parameter exists and has a non-empty value.
+
+        Args:
+            speckle_object: The Speckle object to check
+            parameter_name: Name of the parameter to check
+
+        Returns:
+            bool: True if parameter exists and has a non-empty value
+        """
+        # Get the parameter value
+        parameter_value = PropertyRules.get_parameter_value(speckle_object, parameter_name)
+
+        # Check if parameter exists
+        if parameter_value is None:
+            return False
+
+        # Check if value is an empty string
+        if isinstance(parameter_value, str) and parameter_value.strip() == "":
+            return False
+
+        # Check if value is an empty list or collection
+        if hasattr(parameter_value, "__len__") and len(parameter_value) == 0:
+            return False
+
+        # Additional check for "None" string which can sometimes appear in exports
+        if isinstance(parameter_value, str) and parameter_value.lower() == "none":
+            return False
+
+        return True

tests/test_parameters.py

@@ -415,3 +415,20 @@ class TestParameterHandling:
         """Test negative substring matching on parameter values."""
         v2_obj, _ = test_objects
         assert PropertyRules.is_parameter_value_not_containing(v2_obj, param_name, substring) == expected_result
+
+    @pytest.mark.parametrize(
+        "param_name, expected_result",
+        [
+            ("category", True),  # Parameter exists with non-empty value
+            ("family", True),  # Parameter exists with non-empty value
+            ("non_existent_param", False),  # Parameter doesn't exist
+            # The following would require setup with empty values
+            # ("empty_string_param", False),  # Parameter exists but has empty string value
+            # ("none_string_param", False),  # Parameter exists but has "None" string value
+        ],
+    )
+    def test_parameter_not_empty(self, test_objects, param_name, expected_result):
+        """Test 'not empty' check on parameter values."""
+        v2_obj, _ = test_objects
+
+        assert PropertyRules.is_parameter_value_not_empty(v2_obj, param_name) == expected_result