Change the output checking method in test_func.py. (#18)

* Change the output checking method in test_func.py.

Use redirect_stdout method in test_func.py.
Change the `venv/` into `venv*/` in .gitignore.

* Delete a package that is not used in test_func.py

tests/test_func.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 from contextlib import redirect_stdout
 import io
+import unittest
 import os
 import shutil
 import unittest