'Set up an AppLogger which exercises the C{logger} configuration option.
@type application: L{Componentized}
@param application: The L{Application} object to pass to
L{app.AppLogger.start}.
@type extraLogArgs: C{dict}
@param extraLogArgs: extra values to pass to AppLogger.
@type appLogger: L{AppLogger} class, or a subclass
@param appLogger: factory for L{AppLogger} instances.
@rtype: C{list}
@return: The logs accumulated by the log observer.'

def _setupConfiguredLogger(self, application, extraLogArgs={}, appLogger=app.AppLogger):

    observer = self._makeObserver()
    logArgs = {'logger': (lambda : observer)}
    logArgs.update(extraLogArgs)
    logger = appLogger(logArgs)
    logger.start(application)
    return observer
