'When passing the C{logfile} option, L{app.AppLogger._getLogObserver}
returns a log observer pointing at the specified path.'

def test_getLogObserverFile(self):

    logFiles = _patchTextFileLogObserver(self.patch)
    filename = self.mktemp()
    logger = app.AppLogger({'logfile': filename})
    logger._getLogObserver()
    self.assertEqual(len(logFiles), 1)
    self.assertEqual(logFiles[0].path, os.path.abspath(filename))
