I'm not sure what you are expecting when you have a newline in the input. From your example, it would seem that you want to put a backslash and 'n' in the output, or perhaps to put a newline in the output and have it count as perhaps either one or two characters.

If what you want is the former, this is how I would do it (it will escape all other non-printable characters as well).

$ perl -w
my $string = "this is just a test\nthis is another test\nthis is yet a
+nother test\n";
use Data::Dumper;
{
  local $Data::Dumper::Terse = 1;
  local $Data::Dumper::Useqq = 1;
  local $, = "\n";
  print substr(Dumper($string),1,-2)=~/.{1,5}/gs;
}
__END__
this
is ju
st a
test\
nthis
 is a
nothe
r tes
t\nth
is is
 yet
anoth
er te
st\n
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