type readMaker struct {
	name string
	fn   func(io.Reader) io.Reader
}

var readMakers = []readMaker{
	{"full", func(r io.Reader) io.Reader { return r }},
	{"byte", iotest.OneByteReader},
	{"half", iotest.HalfReader},
	{"data+err", iotest.DataErrReader},
	{"timeout", iotest.TimeoutReader},
}

// Call ReadString (which ends up calling everything else)
// to accumulate the text of a file.
func readLines(b *Reader) string {