Bug fixes, hackage removal, and some pre-commit stylistic

fixes.

- Fixed bugged logic in _STIXBase._check_at_least_one_property(),
and revamped the code to be simpler and clearer.

- Changed custom extension registration to auto-create an
"extension_type" property based on the attribute of that
name on the custom class, if present.

- The custom extension registration change above uncovered
what seemed like a bug in a unit test: a custom extension
was registered, but it was not given an extension type.  The
test used the extension as extension_type="property-extension";
this now causes a standard error about an extra property.  I
fixed the test to assign the custom extension the proper type.

stix2/base.py

@@ -78,20 +78,34 @@ class _STIXBase(collections.abc.Mapping):
         if count > 1 or (at_least_one and count == 0):
             raise MutuallyExclusivePropertiesError(self.__class__, list_of_properties)
 
-    def _check_at_least_one_property(self, list_of_properties=None):
+    def _check_at_least_one_property(self, properties_checked=None):
-        if not list_of_properties:
+        """
-            list_of_properties = sorted(self.__class__._properties.keys())
+        Check whether one or more of the given properties are present.
+
+        :param properties_checked: An iterable of the names of the properties
+            of interest, or None to check against a default list.  The default
+            list includes all properties defined on the object, with some
+            hard-coded exceptions.
+        :raises AtLeastOnePropertyError: If none of the given properties are
+            present.
+        """
+        if properties_checked is None:
+            property_exceptions = {"extensions", "type"}
             if isinstance(self, _Observable):
-                props_to_remove = {"type", "id", "defanged", "spec_version"}
+                property_exceptions |= {"id", "defanged", "spec_version"}
-            else:
-                props_to_remove = {"type"}
 
-            list_of_properties = [prop for prop in list_of_properties if prop not in props_to_remove]
+            properties_checked = self._properties.keys() - property_exceptions
-        current_properties = self.properties_populated()
-        list_of_properties_populated = set(list_of_properties).intersection(current_properties)
 
-        if list_of_properties and (not list_of_properties_populated or list_of_properties_populated == {'extensions'}):
+        elif not isinstance(properties_checked, set):
-            raise AtLeastOnePropertyError(self.__class__, list_of_properties)
+            properties_checked = set(properties_checked)
+
+        if properties_checked:
+            properties_checked_assigned = properties_checked & self.keys()
+
+            if not properties_checked_assigned:
+                raise AtLeastOnePropertyError(
+                    self.__class__, properties_checked
+                )
 
     def _check_properties_dependency(self, list_of_properties, list_of_dependent_properties):
         failed_dependency_pairs = []
@@ -118,8 +132,6 @@ class _STIXBase(collections.abc.Mapping):
             raise ValueError("'custom_properties' must be a dictionary")
 
         extra_kwargs = kwargs.keys() - self._properties.keys()
-        if extra_kwargs and issubclass(cls, stix2.v21._Extension):
-            extra_kwargs = {prop for prop in extra_kwargs if prop != 'extension_type'}
 
         if extra_kwargs and not allow_custom:
             ext_found = False
@@ -129,7 +141,7 @@ class _STIXBase(collections.abc.Mapping):
             for key_id, ext_def in kwargs.get('extensions', {}).items():
                 if (
                     key_id.startswith('extension-definition--') and
-                    ext_def.get('extension_type', '') == 'toplevel-property-extension'
+                    ext_def.get('extension_type') == 'toplevel-property-extension'
                 ):
                     ext_found = True
                     break

stix2/properties.py

@@ -793,8 +793,8 @@ class ExtensionsProperty(DictionaryProperty):
                 else:
                     raise TypeError(
                         "Can't create extension '{}' from {}.".format(
-                            key, type(subvalue)
+                            key, type(subvalue),
-                        )
+                        ),
                     )
 
                 has_custom = has_custom or ext.has_custom
@@ -818,7 +818,7 @@ class ExtensionsProperty(DictionaryProperty):
 
                 if key.startswith('extension-definition--'):
                     _validate_id(
-                        key, self.spec_version, 'extension-definition--'
+                        key, self.spec_version, 'extension-definition--',
                     )
                 elif allow_custom:
                     has_custom = True

stix2/test/v20/test_observed_data.py

@@ -1117,6 +1117,7 @@ def test_process_example_empty_error():
     assert excinfo.value.cls == stix2.v20.Process
     properties_of_process = list(stix2.v20.Process._properties.keys())
     properties_of_process.remove("type")
+    properties_of_process.remove("extensions")
     assert excinfo.value.properties == sorted(properties_of_process)
     msg = "At least one of the ({1}) properties for {0} must be populated."
     msg = msg.format(

stix2/test/v21/test_custom.py

@@ -1237,9 +1237,9 @@ def test_unregistered_new_style_extension():
             "extension-definition--31adb724-a9a4-44b6-8ec2-fd4b181c9507": {
                 "extension-type": "property-extension",
                 "a": 1,
-                "b": True
+                "b": True,
-            }
+            },
-        }
+        },
     }
 
     f = stix2.parse(f_dict, allow_custom=False)
@@ -1508,7 +1508,7 @@ def test_registered_embedded_extension_passes_with_allow_custom_false():
         ],
     )
     class ExtensionFoo1:
-        pass
+        extension_type = "property-extension"
 
     indicator = stix2.v21.Indicator(
         id='indicator--e97bfccf-8970-4a3c-9cd1-5b5b97ed5d0c',

stix2/test/v21/test_observed_data.py

@@ -1218,8 +1218,8 @@ def test_process_example_empty_error():
         stix2.v21.Process()
 
     assert excinfo.value.cls == stix2.v21.Process
-    properties_of_process = list(stix2.v21.Process._properties.keys())
+    properties_of_process = stix2.v21.Process._properties.keys()
-    properties_of_process = [prop for prop in properties_of_process if prop not in ["type", "id", "defanged", "spec_version"]]
+    properties_of_process -= {"type", "id", "defanged", "spec_version", "extensions"}
     assert excinfo.value.properties == sorted(properties_of_process)
     msg = "At least one of the ({1}) properties for {0} must be populated."
     msg = msg.format(

stix2/v21/base.py

@@ -29,17 +29,6 @@ class _Observable(_Observable, _STIXBase21):
 class _Extension(_Extension, _STIXBase21):
     extension_type = None
 
-    def __init__(self, **kwargs):
-        super(_Extension, self).__init__(**kwargs)
-        if getattr(self, "extension_type", None):
-            self._inner["extension_type"] = self.extension_type
-
-    def _check_at_least_one_property(self, list_of_properties=None):
-        new_ext_check = getattr(self, "extension_type", None)
-
-        if new_ext_check is None:
-            super(_Extension, self)._check_at_least_one_property(list_of_properties=list_of_properties)
-
 
 class _DomainObject(_DomainObject, _STIXBase21):
     pass

stix2/v21/common.py

@@ -14,7 +14,7 @@ from ..properties import (
 )
 from ..utils import NOW, _get_dict
 from .base import _STIXBase21
-from .vocab import HASHING_ALGORITHM, EXTENSION_TYPE
+from .vocab import EXTENSION_TYPE, HASHING_ALGORITHM
 
 
 class ExternalReference(_STIXBase21):

stix2/v21/observables.py

@@ -6,6 +6,7 @@ _Observable and do not have a ``_type`` attribute.
 """
 
 from collections import OrderedDict
+from collections.abc import Mapping
 import itertools
 
 from ..custom import _custom_extension_builder, _custom_observable_builder
@@ -20,7 +21,7 @@ from ..properties import (
 from .base import _Extension, _Observable, _STIXBase21
 from .common import GranularMarking
 from .vocab import (
-    ACCOUNT_TYPE, ENCRYPTION_ALGORITHM, HASHING_ALGORITHM,
+    ACCOUNT_TYPE, ENCRYPTION_ALGORITHM, EXTENSION_TYPE, HASHING_ALGORITHM,
     NETWORK_SOCKET_ADDRESS_FAMILY, NETWORK_SOCKET_TYPE,
     WINDOWS_INTEGRITY_LEVEL, WINDOWS_PEBINARY_TYPE, WINDOWS_REGISTRY_DATATYPE,
     WINDOWS_SERVICE_START_TYPE, WINDOWS_SERVICE_STATUS, WINDOWS_SERVICE_TYPE,
@@ -901,5 +902,21 @@ def CustomExtension(type='x-custom-observable-ext', properties=None):
     """Custom STIX Object Extension decorator.
     """
     def wrapper(cls):
+
+        # Auto-create an "extension_type" property from the class attribute, if
+        # it exists.
+        extension_type = getattr(cls, "extension_type", None)
+        if extension_type:
+            extension_type_prop = EnumProperty(
+                EXTENSION_TYPE,
+                required=False,
+                fixed=extension_type,
+            )
+
+            if isinstance(properties, Mapping):
+                properties["extension_type"] = extension_type_prop
+            else:
+                properties.append(("extension_type", extension_type_prop))
+
         return _custom_extension_builder(cls, type, properties, '2.1', _Extension)
     return wrapper

stix2/v21/vocab.py

@@ -99,7 +99,7 @@ EXTENSION_TYPE = [
     EXTENSION_TYPE_NEW_SCO,
     EXTENSION_TYPE_NEW_SRO,
     EXTENSION_TYPE_PROPERTY_EXTENSION,
-    EXTENSION_TYPE_TOPLEVEL_PROPERTY_EXTENSION
+    EXTENSION_TYPE_TOPLEVEL_PROPERTY_EXTENSION,
 ]