Used fixed property for Bundle spec_version

stix2/bundle.py

@@ -1,7 +1,7 @@
 """STIX 2 Bundle object"""
 
 from .base import _STIXBase
-from .properties import IDProperty, TypeProperty
+from .properties import IDProperty, TypeProperty, Property
 
 
 class Bundle(_STIXBase):
@@ -10,9 +10,7 @@ class Bundle(_STIXBase):
     _properties = {
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'spec_version': {
-            'fixed': "2.0",
-        },
+        'spec_version': Property(fixed="2.0"),
         'objects': {},
     }
 

stix2/properties.py

@@ -68,7 +68,7 @@ class Property(object):
     def validate(self, value):
         try:
             value = self.clean(value)
-        except NotImplemetedError:
+        except NotImplementedError:
             pass
         return value
 

stix2/test/test_stix2.py

@@ -471,7 +471,7 @@ def test_bundle_with_wrong_spec_version():
     with pytest.raises(ValueError) as excinfo:
         bundle = stix2.Bundle(spec_version="1.2")
 
-    assert str(excinfo.value) == "Bundle must have spec_version='2.0'."
+    assert str(excinfo.value) == "Invalid value for Bundle 'spec_version': must equal '2.0'."
 
 
 def test_create_bundle(indicator, malware, relationship):