'If there\'s some other error, only call npm install once, and raise a failure'

def test_npm_install_with_unexpected_subprocess_error(self):

    self._mock_paver_sh.side_effect = unexpected_fail_on_npm_install
    with self.assertRaises(BuildFailure):
        node_prereqs_installation()
    actual_calls = self._mock_paver_sh.mock_calls
    self.assertEqual(actual_calls.count(call('npm    install')), 1)
