Fix memory datastore to pass tests

1) 'stix_data' is now optional; you can set up a MemorySink without
needing a starting set of data.
2) Removed stix2-validator calls. The validator fails when called on our
_STIXBase-derived classes because we store timestamps as datetime
objects, while the validator expects strings. Also, this was the only
datastore that used the validator, and we should be consistent across
all of them. The validator can be added back in later.

stix2/sources/memory.py

@@ -22,33 +22,22 @@ import collections
 import json
 import os
 
-from stix2validator import validate_instance
-
 from stix2 import Bundle
 from stix2.sources import DataSink, DataSource, DataStore
 from stix2.sources.filters import Filter
 
 
-def _add(store, stix_data):
+def _add(store, stix_data=None):
     """Adds stix objects to MemoryStore/Source/Sink."""
     if isinstance(stix_data, collections.Mapping):
         # stix objects are in a bundle
-        # verify STIX json data
-        r = validate_instance(stix_data)
         # make dictionary of the objects for easy lookup
-        if r.is_valid:
+        for stix_obj in stix_data["objects"]:
-            for stix_obj in stix_data["objects"]:
+            store.data[stix_obj["id"]] = stix_obj
-                store.data[stix_obj["id"]] = stix_obj
-        else:
-            raise ValueError("Error: data passed was found to not be valid by the STIX 2 Validator: \n%s", r.as_dict())
     elif isinstance(stix_data, list):
         # stix objects are in a list
         for stix_obj in stix_data:
-            r = validate_instance(stix_obj)
+            store.data[stix_obj["id"]] = stix_obj
-            if r.is_valid:
-                store.data[stix_obj["id"]] = stix_obj
-            else:
-                raise ValueError("Error: STIX object %s is not valid under STIX 2 validator.\n%s", stix_obj["id"], r)
     else:
         raise ValueError("stix_data must be in bundle format or raw list")
 
@@ -56,7 +45,7 @@ def _add(store, stix_data):
 class MemoryStore(DataStore):
     """
     """
-    def __init__(self, stix_data):
+    def __init__(self, stix_data=None):
         """
         Notes:
             It doesn't make sense to create a MemoryStore by passing
@@ -83,7 +72,7 @@ class MemoryStore(DataStore):
 class MemorySink(DataSink):
     """
     """
-    def __init__(self, stix_data, _store=False):
+    def __init__(self, stix_data=None, _store=False):
         """
         Args:
             stix_data (dictionary OR list): valid STIX 2.0 content in
@@ -114,7 +103,7 @@ class MemorySink(DataSink):
 
 class MemorySource(DataSource):
 
-    def __init__(self, stix_data, _store=False):
+    def __init__(self, stix_data=None, _store=False):
         """
         Args:
             stix_data (dictionary OR list): valid STIX 2.0 content in
@@ -193,10 +182,5 @@ class MemorySource(DataSource):
         file_path = os.path.abspath(file_path)
         stix_data = json.load(open(file_path, "r"))
 
-        r = validate_instance(stix_data)
+        for stix_obj in stix_data["objects"]:
-
+            self.data[stix_obj["id"]] = stix_obj
-        if r.is_valid:
-            for stix_obj in stix_data["objects"]:
-                    self.data[stix_obj["id"]] = stix_obj
-
-        raise ValueError("Error: STIX data loaded from file (%s) was found to not be validated by STIX 2 Validator.\n%s", file_path, r)