Simplify and centralize temporary file creation

Change-Id: I6674783e7707d66efea05d52381114779f3a64ee
diff --git a/t/zipper.t b/t/zipper.t
index 6147f62..2ee7fab 100644
--- a/t/zipper.t
+++ b/t/zipper.t
@@ -2,7 +2,7 @@
 use warnings;
 use Test::More;
 use File::Spec::Functions qw/catfile/;
-use File::Temp qw/tempfile/;
+use Test::KorAP::XML::TEI qw!korap_tempfile!;
 use IO::Uncompress::Unzip;
 
 use FindBin;
@@ -10,15 +10,10 @@
   unshift @INC, "$FindBin::Bin/../lib";
 };
 
-our %ENV;
-# default: remove temp. file created by func. tempfile
-#  to keep temp. files use e.g. 'KORAPXMLTEI_DONTUNLINK=1 prove -lr t/script.t'
-my $_UNLINK = $ENV{KORAPXMLTEI_DONTUNLINK}?0:1;
-
 require_ok('KorAP::XML::TEI::Zipper');
 
 my $data;
-my ($fh, $outzip) = tempfile("KorAP-XML-TEI_zipper_XXXXXXXXXX", SUFFIX => ".tmp", TMPDIR => 1, UNLINK => $_UNLINK);
+my ($fh, $outzip) = korap_tempfile('zipper');
 
 my $zip = KorAP::XML::TEI::Zipper->new($outzip);
 $fh->close;