Added versioning api, with tests

stix2/base.py

@@ -3,9 +3,10 @@
 import collections
 import datetime as dt
 import json
+import copy
 
 from .exceptions import ExtraFieldsError, ImmutableError, InvalidValueError, \
-                        MissingFieldsError
+                        MissingFieldsError, VersioningError
 from .utils import format_datetime, get_timestamp, NOW
 
 __all__ = ['STIXJSONEncoder', '_STIXBase']
@@ -99,3 +100,33 @@ class _STIXBase(collections.Mapping):
         props = [(k, self[k]) for k in sorted(self._properties) if self.get(k)]
         return "{0}({1})".format(self.__class__.__name__,
                                  ", ".join(["{0!s}={1!r}".format(k, v) for k, v in props]))
+
+#  Versioning API
+
+    def new_version(self, **kwargs):
+        unchangable_properties = []
+        if self.revoked:
+            raise VersioningError("Cannot create a new version of a revoked object")
+        new_obj_inner = copy.deepcopy(self._inner)
+        properties_to_change = kwargs.keys()
+        if "type" in properties_to_change:
+            unchangable_properties.append("type")
+        if "id" in properties_to_change:
+            unchangable_properties.append("id")
+        if "created" in properties_to_change:
+            unchangable_properties.append("created")
+        if "created_by_ref" in properties_to_change:
+            unchangable_properties.append("created_by_ref")
+        if unchangable_properties:
+            raise VersioningError("These properties cannot be changed when making a new version: " + ", ".join(unchangable_properties))
+        if 'modified' not in kwargs:
+            kwargs['modified'] = get_timestamp()
+        new_obj_inner.update(kwargs)
+
+        cls = type(self)
+        return cls(**new_obj_inner)
+
+    def revoke(self):
+        if self.revoked:
+            raise VersioningError("Cannot revoke an already revoked object")
+        return self.new_version(revoked=True)

stix2/exceptions.py

@@ -49,3 +49,10 @@ class ImmutableError(STIXError, ValueError):
 
     def __init__(self):
         super(ImmutableError, self).__init__("Cannot modify properties after creation.")
+
+
+class VersioningError(STIXError, ValueError):
+    """Execption while using the Versioning API"""
+
+    def __init__(self, msg):
+        super(VersioningError, self).__init__(msg)

stix2/test/test_versioning.py

@@ -0,0 +1,107 @@
+import stix2
+import pytest
+
+EXPECTED = """{
+    "created": "2016-04-06T20:03:00.000Z",
+    "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+    "description": "Campaign by Green Group against a series of targets in the financial services sector.",
+    "id": "campaign--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
+    "modified": "2016-04-06T20:03:00.000Z",
+    "name": "Green Group Attacks Against Finance",
+    "type": "campaign"
+}"""
+
+
+def test_making_new_version():
+    campaign_v1 = stix2.Campaign(
+        id="campaign--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
+        created_by_ref="identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+        created="2016-04-06T20:03:00.000Z",
+        modified="2016-04-06T20:03:00.000Z",
+        name="Green Group Attacks Against Finance",
+        description="Campaign by Green Group against a series of targets in the financial services sector."
+    )
+
+    campaign_v2 = campaign_v1.new_version(name="fred")
+
+    assert campaign_v1.id == campaign_v2.id
+    assert campaign_v1.created_by_ref == campaign_v2.created_by_ref
+    assert campaign_v1.created == campaign_v2.created
+    assert campaign_v1.name != campaign_v2.name
+    assert campaign_v2.name == "fred"
+    assert campaign_v1.description == campaign_v2.description
+    assert campaign_v1.modified < campaign_v2.modified
+
+
+def test_revoke():
+    campaign_v1 = stix2.Campaign(
+        id="campaign--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
+        created_by_ref="identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+        created="2016-04-06T20:03:00.000Z",
+        modified="2016-04-06T20:03:00.000Z",
+        name="Green Group Attacks Against Finance",
+        description="Campaign by Green Group against a series of targets in the financial services sector."
+    )
+
+    campaign_v2 = campaign_v1.revoke()
+
+    assert campaign_v1.id == campaign_v2.id
+    assert campaign_v1.created_by_ref == campaign_v2.created_by_ref
+    assert campaign_v1.created == campaign_v2.created
+    assert campaign_v1.name == campaign_v2.name
+    assert campaign_v1.description == campaign_v2.description
+    assert campaign_v1.modified < campaign_v2.modified
+
+    assert campaign_v2.revoked
+
+
+def test_versioning_error_invalid_property():
+    campaign_v1 = stix2.Campaign(
+        id="campaign--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
+        created_by_ref="identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+        created="2016-04-06T20:03:00.000Z",
+        modified="2016-04-06T20:03:00.000Z",
+        name="Green Group Attacks Against Finance",
+        description="Campaign by Green Group against a series of targets in the financial services sector."
+    )
+
+    with pytest.raises(stix2.exceptions.VersioningError) as excinfo:
+        campaign_v2 = campaign_v1.new_version(type="threat-actor")
+
+    str(excinfo.value) == "These properties cannot be changed when making a new version: type"
+
+
+def test_versioning_error_new_version_of_revoked():
+    campaign_v1 = stix2.Campaign(
+        id="campaign--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
+        created_by_ref="identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+        created="2016-04-06T20:03:00.000Z",
+        modified="2016-04-06T20:03:00.000Z",
+        name="Green Group Attacks Against Finance",
+        description="Campaign by Green Group against a series of targets in the financial services sector."
+    )
+
+    campaign_v2 = campaign_v1.revoke()
+
+    with pytest.raises(stix2.exceptions.VersioningError) as excinfo:
+        campaign_v3 = campaign_v2.new_version(name="barney")
+
+    str(excinfo.value) == "Cannot create a new version of a revoked object"
+
+
+def test_versioning_error_revoke_of_revoked():
+    campaign_v1 = stix2.Campaign(
+        id="campaign--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
+        created_by_ref="identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+        created="2016-04-06T20:03:00.000Z",
+        modified="2016-04-06T20:03:00.000Z",
+        name="Green Group Attacks Against Finance",
+        description="Campaign by Green Group against a series of targets in the financial services sector."
+    )
+
+    campaign_v2 = campaign_v1.revoke()
+
+    with pytest.raises(stix2.exceptions.VersioningError) as excinfo:
+        campaign_v3 = campaign_v2.revoke()
+
+    str(excinfo.value) == "Cannot revoke an already revoked object"