Clean up code/comments

setup.py

@@ -3,6 +3,7 @@ from setuptools import setup, find_packages
 
 install_requires = [
     'pytz',
+    'six',
 ]
 
 setup(

stix2/properties.py

@@ -1,6 +1,6 @@
 import re
 import uuid
-import sys
+from six import PY2
 
 
 class Property(object):
@@ -93,6 +93,7 @@ class ListProperty(Property):
         except ValueError:
             raise
 
+        # STIX spec forbids empty lists
         if len(list_) < 1:
             raise ValueError("must not be empty.")
 
@@ -109,16 +110,21 @@ class ListProperty(Property):
         return list_
 
     def clean(self, value):
+        try:
+            iter(value)
+        except TypeError:
+            raise ValueError("must be an iterable.")
+
         try:
             return [self.contained(**x) if type(x) is dict else self.contained(x) for x in value]
         except TypeError:
-            raise ValueError("must be an iterable over a type whose constructor creates an object from the value.")
+            raise ValueError("the type of objects in the list must have a constructor that creates an object from the value.")
 
 
 class StringProperty(Property):
 
     def __init__(self, **kwargs):
-        if sys.version_info[0] == 2:
+        if PY2:
             self.string_type = unicode
         else:
             self.string_type = str

stix2/test/test_properties.py

@@ -90,27 +90,39 @@ def test_id_property():
     assert idprop.validate(idprop.default())
 
 
-def test_boolean_property():
+@pytest.mark.parametrize("value", [
+    True,
+    False,
+    'True',
+    'False',
+    'true',
+    'false',
+    'TRUE',
+    'FALSE',
+    'T',
+    'F',
+    't',
+    'f',
+    1,
+    0,
+])
+def test_boolean_property_valid(value):
     bool_prop = BooleanProperty()
 
-    assert bool_prop.validate(True) is not None
-    assert bool_prop.validate(False) is not None
-    assert bool_prop.validate('True') is not None
-    assert bool_prop.validate('False') is not None
-    assert bool_prop.validate('true') is not None
-    assert bool_prop.validate('false') is not None
-    assert bool_prop.validate('TRUE') is not None
-    assert bool_prop.validate('FALSE') is not None
-    assert bool_prop.validate('T') is not None
-    assert bool_prop.validate('F') is not None
-    assert bool_prop.validate('t') is not None
-    assert bool_prop.validate('f') is not None
-    assert bool_prop.validate(1) is not None
-    assert bool_prop.validate(0) is not None
-    for invalid in ('abc', ['false'], {'true': 'true'}, 2, -1):
-        print(invalid)
-        with pytest.raises(ValueError):
-            bool_prop.validate(invalid)
+    assert bool_prop.validate(value) is not None
+
+
+@pytest.mark.parametrize("value", [
+    'abc',
+    ['false'],
+    {'true': 'true'},
+    2,
+    -1,
+])
+def test_boolean_property_invalid(value):
+    bool_prop = BooleanProperty()
+    with pytest.raises(ValueError):
+        bool_prop.validate(value)
 
 
 def test_reference_property():