Pickle-proof stix objects

stix2/base.py

@@ -185,7 +185,13 @@ class _STIXBase(collections.Mapping):
 
     # Handle attribute access just like key access
     def __getattr__(self, name):
-        if name in self:
+        # Pickle-proofing: pickle invokes this on uninitialized instances (i.e.
+        # __init__ has not run).  So no "self" attributes are set yet.  The
+        # usual behavior of this method reads an __init__-assigned attribute,
+        # which would cause infinite recursion.  So this check disables all
+        # attribute reads until the instance has been properly initialized.
+        unpickling = "_inner" not in self.__dict__
+        if not unpickling and name in self:
             return self.__getitem__(name)
         raise AttributeError("'%s' object has no attribute '%s'" %
                              (self.__class__.__name__, name))

stix2/test/test_pickle.py

@@ -0,0 +1,17 @@
+import pickle
+
+import stix2
+
+
+def test_pickling():
+    """
+    Ensure a pickle/unpickle cycle works okay.
+    """
+    identity = stix2.Identity(
+        id="identity--d66cb89d-5228-4983-958c-fa84ef75c88c",
+        name="alice",
+        description="this is a pickle test",
+        identity_class="some_class"
+    )
+
+    pickle.loads(pickle.dumps(identity))