}
    set c [chan create read [namespace which driver]]
    chan configure $c -encoding utf-8
    while {![eof $c]} {
        read $c 15
    }
    close $c
} {}
test io-12.7 {ReadChars: too many chars read [bc5b790099]} {
    proc driver {cmd args} {
        variable buffer
        variable index
        set chan [lindex $args 0]
        switch -- $cmd {
            initialize {
                set index($chan) 0
                set buffer($chan) [encoding convertto utf-8 \
                        [string repeat \uBEEF 10]....\uBEEF]
                return {initialize finalize watch read}
            }
            finalize {
                unset index($chan) buffer($chan)
                return
            }
            watch {}
            read {
                set n [lindex $args 1]
                set new [expr {$index($chan) + $n}]
                set result [string range $buffer($chan) $index($chan) $new-1]
                set index($chan) $new
                return $result
            }
        }
    }
    set c [chan create read [namespace which driver]]
    chan configure $c -encoding utf-8
    while {![eof $c]} {
        read $c 7
    }
    close $c
} {}

test io-13.1 {TranslateInputEOL: cr mode} {} {
    set f [open $path(test1) w]
    fconfigure $f -translation lf
    puts -nonewline $f "abcd\rdef\r"
    close $f