diff --git a/tools/checker/common/testing.py b/tools/checker/common/testing.py
new file mode 100644
index 0000000..1299c07
--- /dev/null
+++ b/tools/checker/common/testing.py
@@ -0,0 +1,22 @@
+# Copyright (C) 2014 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+def ToUnicode(string):
+  """ Converts a string into Unicode.
+
+  This is a delegate function for the built-in `unicode`. It checks if the input
+  is not `None`, because `unicode` turns it into an actual "None" string.
+  """
+  assert string is not None
+  return unicode(string)