Changed emitted deprecation warnings to a custom DeprecationWarning

subclass.  Changed the unit test to test for that specific
warning category, instead of any DeprecationWarning.

stix2/exceptions.py

@@ -226,3 +226,10 @@ class MarkingNotFoundError(STIXError):
     def __str__(self):
         msg = "Marking {0} was not found in {1}!"
         return msg.format(self.key, self.cls.__class__.__name__)
+
+
+class STIXDeprecationWarning(DeprecationWarning):
+    """
+    Represents usage of a deprecated component of a STIX specification.
+    """
+    pass

stix2/test/v21/test_observed_data.py

@@ -1378,7 +1378,8 @@ def test_new_version_with_related_objects():
 
 
 def test_objects_deprecation():
-    with pytest.deprecated_call():
+    with pytest.warns(stix2.exceptions.STIXDeprecationWarning):
+
         stix2.v21.ObservedData(
             first_observed="2016-03-12T12:00:00Z",
             last_observed="2016-03-12T12:00:00Z",

stix2/v21/sdo.py

@@ -8,7 +8,7 @@ from six.moves.urllib.parse import quote_plus
 
 from ..core import STIXDomainObject
 from ..custom import _custom_object_builder
-from ..exceptions import PropertyPresenceError
+from ..exceptions import PropertyPresenceError, STIXDeprecationWarning
 from ..properties import (
     BinaryProperty, BooleanProperty, EmbeddedObjectProperty, EnumProperty,
     FloatProperty, IDProperty, IntegerProperty, ListProperty,
@@ -578,7 +578,7 @@ class ObservedData(STIXDomainObject):
             warnings.warn(
                 "The 'objects' property of observed-data is deprecated in "
                 "STIX 2.1.",
-                DeprecationWarning,
+                STIXDeprecationWarning,
             )
 
         super(ObservedData, self).__init__(*args, **kwargs)

tox.ini

@@ -11,7 +11,7 @@ deps =
   taxii2-client
   medallion
 commands =
-  pytest --cov=stix2 stix2/test/ --cov-report term-missing
+  pytest --cov=stix2 stix2/test/ --cov-report term-missing -W ignore::stix2.exceptions.STIXDeprecationWarning
 
 passenv = CI TRAVIS TRAVIS_*