diff --git a/stix2/test/test_properties.py b/stix2/test/test_properties.py
index b8a589c..60a42e6 100644
--- a/stix2/test/test_properties.py
+++ b/stix2/test/test_properties.py
@@ -71,7 +71,9 @@ def test_property_fixed_and_required():
 def test_list_property_property_type():
     p = ListProperty(StringProperty)
 
-    assert p.clean(['abc', 'xyz'], False)
+    result = p.clean(['abc', 'xyz'], False)
+    assert result == (['abc', 'xyz'], False)
+
     with pytest.raises(ValueError):
         p.clean([], False)
 
@@ -89,7 +91,8 @@ def test_list_property_property_type_custom():
         TestObj(foo="xyz"),
     ]
 
-    assert p.clean(objs_custom, True)
+    result = p.clean(objs_custom, True)
+    assert result == (objs_custom, True)
 
     with pytest.raises(CustomContentError):
         p.clean(objs_custom, False)
@@ -99,7 +102,8 @@ def test_list_property_property_type_custom():
         {"foo": "xyz"},
     ]
 
-    assert p.clean(dicts_custom, True)
+    result = p.clean(dicts_custom, True)
+    assert result == (objs_custom, True)
 
     with pytest.raises(ExtraPropertiesError):
         p.clean(dicts_custom, False)
@@ -114,10 +118,12 @@ def test_list_property_object_type():
     p = ListProperty(TestObj)
 
     objs = [TestObj(foo="abc"), TestObj(foo="xyz")]
-    assert p.clean(objs, False)
+    result = p.clean(objs, False)
+    assert result == (objs, False)
 
     dicts = [{"foo": "abc"}, {"foo": "xyz"}]
-    assert p.clean(dicts, False)
+    result = p.clean(dicts, False)
+    assert result == (objs, False)
 
 
 def test_list_property_object_type_custom():
@@ -133,7 +139,8 @@ def test_list_property_object_type_custom():
         TestObj(foo="xyz"),
     ]
 
-    assert p.clean(objs_custom, True)
+    result = p.clean(objs_custom, True)
+    assert result == (objs_custom, True)
 
     with pytest.raises(CustomContentError):
         p.clean(objs_custom, False)
@@ -143,7 +150,8 @@ def test_list_property_object_type_custom():
         {"foo": "xyz"},
     ]
 
-    assert p.clean(dicts_custom, True)
+    result = p.clean(dicts_custom, True)
+    assert result == (objs_custom, True)
 
     with pytest.raises(ExtraPropertiesError):
         p.clean(dicts_custom, False)
diff --git a/stix2/test/v20/test_properties.py b/stix2/test/v20/test_properties.py
index 5c57ed0..af1ffec 100644
--- a/stix2/test/v20/test_properties.py
+++ b/stix2/test/v20/test_properties.py
@@ -16,6 +16,7 @@ from stix2.v20.common import MarkingProperty
 
 from . import constants
 
+
 ID_PROP = IDProperty('my-type', spec_version="2.0")
 MY_ID = 'my-type--232c9d3f-49fc-4440-bb01-607f638778e7'
 
diff --git a/stix2/test/v21/test_properties.py b/stix2/test/v21/test_properties.py
index f963944..aa3624b 100644
--- a/stix2/test/v21/test_properties.py
+++ b/stix2/test/v21/test_properties.py
@@ -23,23 +23,6 @@ def test_dictionary_property():
         p.clean({})
 
 
-def test_string_property():
-    prop = StringProperty()
-
-    assert prop.clean('foobar')
-    assert prop.clean(1)
-    assert prop.clean([1, 2, 3])
-
-
-def test_type_property():
-    prop = TypeProperty('my-type')
-
-    assert prop.clean('my-type')
-    with pytest.raises(ValueError):
-        prop.clean('not-my-type')
-    assert prop.clean(prop.default())
-
-
 ID_PROP = IDProperty('my-type', spec_version="2.1")
 MY_ID = 'my-type--232c9d3f-49fc-4440-bb01-607f638778e7'