Tests: Fix for Oracle

Author: erezsh

tests/test_diff_tables.py

@@ -513,6 +513,9 @@ def setUp(self):
         ]
         for i in range(0, 10000, 1000):
             a = ArithAlphanumeric(numberToAlphanum(i), max_len=10)
+            if not a and isinstance(self.connection, db.Oracle):
+                # Skip empty string, because Oracle treats it as NULL ..
+                continue
             queries.append(f"INSERT INTO {self.table_src} VALUES ('{a}', '{i}')")
 
         queries += [
@@ -561,6 +564,9 @@ def setUp(self):
         ]
         for i in range(0, 10000, 1000):
             a = ArithAlphanumeric(numberToAlphanum(i * i))
+            if not a and isinstance(self.connection, db.Oracle):
+                # Skip empty string, because Oracle treats it as NULL ..
+                continue
             queries.append(f"INSERT INTO {self.table_src} VALUES ('{a}', '{i}')")
 
         queries += [