Confirm unit tests run properly individually & fix test_keystore

"test_keystore.py" logged TUF messages if run individually.

tuf/tests/test_keystore.py

@@ -19,12 +19,19 @@
 import unittest
 import shutil
 import os
+import logging
 
 import tuf.repo.keystore
 import tuf.rsa_key
 import tuf.formats
 import tuf.util
 
+logger = logging.getLogger('tuf')
+
+# Disable all logging calls of level CRITICAL and below.
+# Comment the line below to enable logging.
+logging.disable(logging.CRITICAL)
+
 # We'll need json module for testing '_encrypt()' and '_decrypt()'
 # internal function.
 json = tuf.util.import_json()