use strict;
use warnings;

use Test::More tests => 4;

open (F, "echo -e 'a\nb\nc'|");
my $line = <F>;
is ($line, "a\n", "a in main()");
while ($line) {
    if ($line =~ /a/) {
        SubOut (\*F);
    }
    ok (eof (F), "F is exhausted");
    $line = <F>;
}
close (F);

sub SubOut {
    my $fh = shift;
    my $s_line = <$fh>;
    while ($s_line) {
        like ($s_line, qr/[bc]\n$/, "b or c matched in SubOut()");
        $s_line = <$fh>;
    }
}