Add Exception for missing values.

stix2/base.py

@@ -4,7 +4,7 @@ import collections
 import datetime as dt
 import json
 
-from .exceptions import STIXValueError
+from .exceptions import STIXValueError, MissingFieldsError
 from .utils import format_datetime, get_timestamp, NOW
 
 __all__ = ['STIXJSONEncoder', '_STIXBase']
@@ -46,7 +46,6 @@ class _STIXBase(collections.Mapping):
 
     def __init__(self, **kwargs):
         cls = self.__class__
-        class_name = cls.__name__
 
         # Use the same timestamp for any auto-generated datetimes
         self.__now = get_timestamp()
@@ -59,9 +58,7 @@ class _STIXBase(collections.Mapping):
         required_fields = get_required_properties(cls._properties)
         missing_kwargs = set(required_fields) - set(kwargs)
         if missing_kwargs:
-            msg = "Missing required field(s) for {type}: ({fields})."
+            raise MissingFieldsError(cls, missing_kwargs)
-            field_list = ", ".join(x for x in sorted(list(missing_kwargs)))
-            raise ValueError(msg.format(type=class_name, fields=field_list))
 
         for prop_name, prop_metadata in cls._properties.items():
             self._check_property(prop_name, prop_metadata, kwargs)

stix2/exceptions.py

@@ -6,6 +6,7 @@ class STIXValueError(STIXError, ValueError):
     """An invalid value was provided to a STIX object's __init__."""
 
     def __init__(self, cls, prop_name, reason):
+        super(STIXValueError, self).__init__()
         self.cls = cls
         self.prop_name = prop_name
         self.reason = reason
@@ -13,3 +14,17 @@ class STIXValueError(STIXError, ValueError):
     def __str__(self):
         msg = "Invalid value for {0.cls.__name__} '{0.prop_name}': {0.reason}"
         return msg.format(self)
+
+
+class MissingFieldsError(STIXError, ValueError):
+    """Missing required field(s) when construting STIX object."""
+
+    def __init__(self, cls, fields):
+        super(MissingFieldsError, self).__init__()
+        self.cls = cls
+        self.fields = sorted(list(fields))
+
+    def __str__(self):
+        msg = "Missing required field(s) for {0}: ({1})."
+        return msg.format(self.cls.__name__,
+                          ", ".join(x for x in self.fields))

stix2/test/test_external_reference.py

@@ -107,6 +107,9 @@ def test_external_reference_offline():
 
 
 def test_external_reference_source_required():
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(stix2.exceptions.MissingFieldsError) as excinfo:
         stix2.ExternalReference()
+
+    assert excinfo.value.cls == stix2.ExternalReference
+    assert excinfo.value.fields == ["source_name"]
     assert str(excinfo.value) == "Missing required field(s) for ExternalReference: (source_name)."

stix2/test/test_indicator.py

@@ -87,14 +87,20 @@ def test_indicator_id_must_start_with_indicator():
 
 
 def test_indicator_required_fields():
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(stix2.exceptions.MissingFieldsError) as excinfo:
         stix2.Indicator()
+
+    assert excinfo.value.cls == stix2.Indicator
+    assert excinfo.value.fields == ["labels", "pattern"]
     assert str(excinfo.value) == "Missing required field(s) for Indicator: (labels, pattern)."
 
 
 def test_indicator_required_field_pattern():
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(stix2.exceptions.MissingFieldsError) as excinfo:
         stix2.Indicator(labels=['malicious-activity'])
+
+    assert excinfo.value.cls == stix2.Indicator
+    assert excinfo.value.fields == ["pattern"]
     assert str(excinfo.value) == "Missing required field(s) for Indicator: (pattern)."
 
 

stix2/test/test_kill_chain_phases.py

@@ -36,23 +36,29 @@ def test_kill_chain_example():
 
 def test_kill_chain_required_fields():
 
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(stix2.exceptions.MissingFieldsError) as excinfo:
         stix2.KillChainPhase()
 
+    assert excinfo.value.cls == stix2.KillChainPhase
+    assert excinfo.value.fields == ["kill_chain_name", "phase_name"]
     assert str(excinfo.value) == "Missing required field(s) for KillChainPhase: (kill_chain_name, phase_name)."
 
 
 def test_kill_chain_required_field_chain_name():
 
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(stix2.exceptions.MissingFieldsError) as excinfo:
         stix2.KillChainPhase(phase_name="weaponization")
 
+    assert excinfo.value.cls == stix2.KillChainPhase
+    assert excinfo.value.fields == ["kill_chain_name"]
     assert str(excinfo.value) == "Missing required field(s) for KillChainPhase: (kill_chain_name)."
 
 
 def test_kill_chain_required_field_phase_name():
 
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(stix2.exceptions.MissingFieldsError) as excinfo:
         stix2.KillChainPhase(kill_chain_name="lockheed-martin-cyber-kill-chain")
 
+    assert excinfo.value.cls == stix2.KillChainPhase
+    assert excinfo.value.fields == ["phase_name"]
     assert str(excinfo.value) == "Missing required field(s) for KillChainPhase: (phase_name)."

stix2/test/test_malware.py

@@ -71,14 +71,20 @@ def test_malware_id_must_start_with_malware():
 
 
 def test_malware_required_fields():
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(stix2.exceptions.MissingFieldsError) as excinfo:
         stix2.Malware()
+
+    assert excinfo.value.cls == stix2.Malware
+    assert excinfo.value.fields == ["labels", "name"]
     assert str(excinfo.value) == "Missing required field(s) for Malware: (labels, name)."
 
 
 def test_malware_required_field_name():
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(stix2.exceptions.MissingFieldsError) as excinfo:
         stix2.Malware(labels=['ransomware'])
+
+    assert excinfo.value.cls == stix2.Malware
+    assert excinfo.value.fields == ["name"]
     assert str(excinfo.value) == "Missing required field(s) for Malware: (name)."
 
 

stix2/test/test_relationship.py

@@ -74,23 +74,26 @@ def test_relationship_id_must_start_with_relationship():
 
 
 def test_relationship_required_field_relationship_type():
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(stix2.exceptions.MissingFieldsError) as excinfo:
         stix2.Relationship()
     assert str(excinfo.value) == "Missing required field(s) for Relationship: (relationship_type, source_ref, target_ref)."
 
 
 def test_relationship_missing_some_required_fields():
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(stix2.exceptions.MissingFieldsError) as excinfo:
         stix2.Relationship(relationship_type='indicates')
     assert str(excinfo.value) == "Missing required field(s) for Relationship: (source_ref, target_ref)."
 
 
 def test_relationship_required_field_target_ref():
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(stix2.exceptions.MissingFieldsError) as excinfo:
         stix2.Relationship(
             relationship_type='indicates',
             source_ref=INDICATOR_ID
         )
+
+    assert excinfo.value.cls == stix2.Relationship
+    assert excinfo.value.fields == ["target_ref"]
     assert str(excinfo.value) == "Missing required field(s) for Relationship: (target_ref)."