sub separate_stores
{
  my (@li_stores, @ff_stores);
  my $stores_file = File::HomeDir->my_home . "/example/data/example.csv";
  open my $fh, "<", $stores_file or die "$stores_file: $!";

# So at this point we know that you were able to successfully
# open example.csv, because you tested your open.

  my $csv = Text::CSV->new ({
    binary    => 1,
    auto_diag => 1,
  });

# Also know that if your parsing of CSV generates an error,
# that error will be spat to the screen for us.  Good.

  my $count_li = 0;
  my $count_ff = 0;

  $csv ->getline ($fh);

# We don't know if the preceding line returned 'undef',
# indicating an empty CSV file.  We also don't know if 
# it really stripped away a header row, or something useful
# instead.  We also don't know if there is any more CSV remaining
# after processing that first line.

#################
# Change the preceding line "$csv ->getline ($fh);" to the following,
# for better diagnostics:
#
  my $head = $csv->getline($fh) or die "Empty CSV file $!\n";
  warn "CSV header line contained (@{$head})\n" if $ENV{MYTEST_DEBUG};
  die "Nothing found after CSV header line.\n" if $csv->eof;
#
# Now set an environment variable "MYTEST_DEBUG" true, and re-run your test.
#################

  while (my $row = $csv->getline ($fh)) {

# Your 'while' loop will never be entered if you're already at
# the end of file.  We don't know if that's an issue, because you
# didn't explicitly test what happened when you stripped the first
# CSV line.

    if ($row->[1] eq "li") {
      $li_stores[$count_li] = $row->[0];
      $count_li ++;
    } else {
      $ff_stores[$count_ff] = $row->[0];
      $count_ff ++;
    }
  }
  close $fh;
  return (\@li_stores, \@ff_stores);
}