def METHOD_NAME(self) -> None:
    """
    Returned L{FileLogObserver} has the correct outFile.
    """
    with StringIO() as fileHandle:
        observer = textFileLogObserver(fileHandle, timeFormat="%f")
        observer(dict(log_format="XYZZY", log_time=112345.6))
        self.assertEqual(fileHandle.getvalue(), "600000 [-#-] XYZZY\n")