'Check that openForReading returns an object providing C{ftp.IReadFile}.'

def test_openForReading(self):

    self.createFile('file.txt')
    d = self.shell.openForReading(('file.txt',))
    def cb(res):
        self.assertTrue(ftp.IReadFile.providedBy(res))
    d.addCallback(cb)
    return d
