'Test validate with a relative path to an existing file.'

def test_validate_exists_rel(self, klass, os_mock, monkeypatch):

    monkeypatch.setattr('qutebrowser.config.configtypes.standarddir.config', (lambda : '/home/foo/.config/'))
    os_mock.path.isfile.return_value = True
    os_mock.path.isabs.return_value = False
    klass().validate('foobar')
    os_mock.path.join.assert_called_once_with('/home/foo/.config/', 'foobar')
