Tests should all use test HA

tests/components/test_shell_command.py

@@ -10,15 +10,16 @@ import unittest
 from unittest.mock import patch
 from subprocess import SubprocessError
 
-from homeassistant import core
 from homeassistant.components import shell_command
 
+from tests.common import get_test_home_assistant
+
 
 class TestShellCommand(unittest.TestCase):
     """ Test the demo module. """
 
     def setUp(self):  # pylint: disable=invalid-name
-        self.hass = core.HomeAssistant()
+        self.hass = get_test_home_assistant()
 
     def tearDown(self):  # pylint: disable=invalid-name
         """ Stop down stuff we started. """