diff --git a/src/caosdb/apiutils.py b/src/caosdb/apiutils.py
index e6b4dc4ef43a8907f0d04acc3f1f46eb25496a2e..21a8cc7ca700a8b119786dbef082db286ead5d57 100644
--- a/src/caosdb/apiutils.py
+++ b/src/caosdb/apiutils.py
@@ -30,15 +30,15 @@ Some simplified functions for generation of records etc.
 
 import sys
 import tempfile
-from collections.abc import Iterable
 import warnings
+from collections.abc import Iterable
 from subprocess import call
 
 from caosdb.common.datatype import (BOOLEAN, DATETIME, DOUBLE, FILE, INTEGER,
                                     REFERENCE, TEXT, is_reference)
 from caosdb.common.models import (Container, Entity, File, Property, Query,
-                                  Record, RecordType, get_config,
-                                  execute_query)
+                                  Record, RecordType, execute_query,
+                                  get_config)
 
 
 def new_record(record_type, name=None, description=None,
@@ -632,16 +632,12 @@ def compare_entities(old_entity: Entity, new_entity: Entity):
                 newdiff["properties"][prop.name]["importance"] = \
                     new_entity.get_importance(prop.name)
 
-            if ((prop.datatype is not None and
-                    matching[0].datatype is not None) and
-                    (prop.datatype != matching[0].datatype)):
+            if (prop.datatype != matching[0].datatype):
                 olddiff["properties"][prop.name]["datatype"] = prop.datatype
                 newdiff["properties"][prop.name]["datatype"] = \
                     matching[0].datatype
 
-            if ((prop.value is not None and
-                    matching[0].value is not None) and
-                    (prop.value != matching[0].value)):
+            if (prop.value != matching[0].value):
                 olddiff["properties"][prop.name]["value"] = prop.value
                 newdiff["properties"][prop.name]["value"] = \
                     matching[0].value
@@ -723,6 +719,7 @@ def apply_to_ids(entities, func):
     entities : list of Entity
     func : function with one parameter.
     """
+
     for entity in entities:
         _apply_to_ids_of_entity(entity, func)
 
diff --git a/unittests/test_apiutils.py b/unittests/test_apiutils.py
index 78ad9712ca9e1196e8bce6acd6d5ec219f9ef0b8..717595d049a5a7c27b644dc6079d02efa1cefb71 100644
--- a/unittests/test_apiutils.py
+++ b/unittests/test_apiutils.py
@@ -26,11 +26,14 @@
 # Test apiutils
 # A. Schlemmer, 02/2018
 
-import caosdb as db
 import pickle
 import tempfile
-from caosdb.apiutils import apply_to_ids, create_id_query, resolve_reference, compare_entities
+
+import caosdb as db
 import caosdb.apiutils
+from caosdb.apiutils import (apply_to_ids, compare_entities, create_id_query,
+                             resolve_reference)
+
 from .test_property import testrecord
 
 
@@ -67,7 +70,8 @@ def test_apply_to_ids():
 
 def test_id_query():
     ids = [1, 2, 3, 4, 5]
-    assert create_id_query(ids) == 'FIND ENTITY WITH ID=1 OR ID=2 OR ID=3 OR ID=4 OR ID=5'
+    assert create_id_query(ids) == 'FIND ENTITY WITH ID=1 OR ID=2 OR ID=3 OR '\
+        'ID=4 OR ID=5'
 
 
 def test_resolve_reference():
@@ -77,8 +81,10 @@ def test_resolve_reference():
     prop = db.Property(id=1, datatype=db.REFERENCE, value=100)
     prop.is_valid = lambda: True
     items = [200, 300, 400]
-    prop_list = db.Property(datatype=db.LIST(db.REFERENCE), value=items)
-    prop_list2 = db.Property(datatype=db.LIST(db.REFERENCE), value=[db.Record(id=500)])
+    prop_list = db.Property(datatype=db.LIST(db.REFERENCE),
+                            value=items)
+    prop_list2 = db.Property(datatype=db.LIST(db.REFERENCE),
+                             value=[db.Record(id=500)])
     resolve_reference(prop)
     resolve_reference(prop_list)
     resolve_reference(prop_list2)
@@ -86,6 +92,7 @@ def test_resolve_reference():
     assert isinstance(prop.value, db.Entity)
 
     prop_list_ids = []
+
     for i in prop_list.value:
         prop_list_ids.append(i.id)
         assert isinstance(i, db.Entity)
@@ -114,6 +121,8 @@ def test_compare_entities():
     r2.add_property("test", value=2)
     r1.add_property("tests", value=3)
     r2.add_property("tests", value=45)
+    r1.add_property("tester", value=3)
+    r2.add_property("tester", )
     r1.add_property("tests_234234", value=45)
     r2.add_property("tests_TT", value=45)
 
@@ -121,8 +130,8 @@ def test_compare_entities():
 
     assert len(diff_r1["parents"]) == 1
     assert len(diff_r2["parents"]) == 0
-    assert len(diff_r1["properties"]) == 2
-    assert len(diff_r2["properties"]) == 2
+    assert len(diff_r1["properties"]) == 3
+    assert len(diff_r2["properties"]) == 3
 
     assert "test" not in diff_r1["properties"]
     assert "test" not in diff_r2["properties"]
@@ -130,5 +139,8 @@ def test_compare_entities():
     assert "tests" in diff_r1["properties"]
     assert "tests" in diff_r2["properties"]
 
+    assert "tester" in diff_r1["properties"]
+    assert "tester" in diff_r2["properties"]
+
     assert "tests_234234" in diff_r1["properties"]
     assert "tests_TT" in diff_r2["properties"]
diff --git a/unittests/test_property.py b/unittests/test_property.py
index 834b1be582c58c60f70331de9cb0d0d6414fd6c9..7c756117765e510587c00d818e39fb3945d44c53 100644
--- a/unittests/test_property.py
+++ b/unittests/test_property.py
@@ -24,15 +24,18 @@
 # ** end header
 #
 """Tests for the Property class."""
+import os
+
 import caosdb as db
 from caosdb import Entity, Property, Record
 # pylint: disable=missing-docstring
 from lxml import etree
 
 parser = etree.XMLParser(remove_comments=True)
-testrecord = Record._from_xml(Record(),
-                              etree.parse("unittests/test_record.xml",
-                                          parser).getroot())
+testrecord = Record._from_xml(
+    Record(),
+    etree.parse(os.path.join(os.path.dirname(__file__), "test_record.xml"),
+                parser).getroot())
 
 
 def test_is_entity():
@@ -48,7 +51,8 @@ def test_instance_variables():
 
 
 def test_null_empty_text_value_1():
-    assert testrecord.get_property("LISTofTEXT").value == ["One", "Two", "Three", None, ""]
+    assert testrecord.get_property("LISTofTEXT").value == ["One", "Two",
+                                                           "Three", None, ""]
 
 
 def test_null_empty_text_value_2():