--- a
+++ b/tests/surrogates/generators/util.py
@@ -0,0 +1,15 @@
+from deidentify.surrogates.generators import RandomData
+
+class RandomDataMock(RandomData):
+
+    def digit(self, digits='1'):
+        return digits
+
+    def ascii_lowercase(self):
+        return 'c'
+
+    def ascii_uppercase(self):
+        return 'C'
+
+    def choice(self, seq):
+        return seq[0]