Index: twikiplugins/UnitTestContrib/test/unit/Fn_URLPARAM.pm
===================================================================
--- twikiplugins/UnitTestContrib/test/unit/Fn_URLPARAM.pm	(revision 0)
+++ twikiplugins/UnitTestContrib/test/unit/Fn_URLPARAM.pm	(revision 0)
@@ -0,0 +1,156 @@
+use strict;
+
+# tests for the correct expansion of URLPARAM
+
+package Fn_URLPARAM;
+
+use base qw( TWikiFnTestCase );
+
+use TWiki;
+use Error qw( :try );
+
+sub new {
+    my $self = shift()->SUPER::new('GROUPS', @_);
+    return $self;
+}
+
+sub set_up {
+    my $this = shift;
+    $this->SUPER::set_up(@_);
+}
+
+sub test_default {
+    my $this = shift;
+
+    my $str;
+
+    # test default parameter
+
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('', "$str");
+
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo" default="0"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('0', "$str");
+
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo" default=""}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('', "$str");
+
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo" default="bar"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('bar', "$str");
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'foo', -value=>'bar');
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo" default="0"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('bar', "$str");
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'foo', -value=>'0');
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo" default="bar"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('0', "$str");
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'foo', -value=>'');
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo" default="bar"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('', "$str");
+}
+
+sub test_encode {
+    my $this = shift;
+
+    my $str;
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'foo', -value=>'&?*!"');
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo" encode="entity"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('&?*!"', "$str");
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'foo', -value=>'&?*!" ');
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo" encode="url"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('%26%3f*!%22%20', "$str");
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'foo', -value=>'&?*!" ');
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo" encode="quote"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('&?*!\" ', "$str");
+}
+
+sub test_defaultencode {
+    my $this = shift;
+
+    my $str;
+
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo" default="&?*!\" " encode="entity"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('&?*!" ', "$str");
+
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo" default="&?*!\" " encode="url"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('&?*!" ', "$str");
+
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"foo" default="&?*!\" " encode="quote"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals('&?*!" ', "$str");
+
+
+}
+
+sub test_multiple {
+    my $this = shift;
+
+    my $str;
+
+    my @multiple=('foo','bar','baz');
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'multi', -value=>['foo','bar','baz']);
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"multi" multiple="on"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals("foo\nbar\nbaz", "$str");
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'multi', -value=>['foo','bar','baz']);
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"multi" multiple="on" separator=","}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals("foo,bar,baz", "$str");
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'multi', -value=>['foo','bar','baz']);
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"multi" multiple="on" separator=""}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals("foobarbaz", "$str");
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'multi', -value=>['foo','bar','baz']);
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"multi" multiple="-$item-" separator=" "}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals("-foo- -bar- -baz-", "$str");
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'multi', -value=>['foo','bar','baz']);
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"multi" multiple="-$item-" separator=""}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals("-foo--bar--baz-", "$str");
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'multi', -value=>['foo','bar','baz']);
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"multi" multiple="-$item-"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals("-foo-\n-bar-\n-baz-", "$str");
+}
+
+sub test_newline {
+    my $this = shift;
+
+    my $str;
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'textarea', -value=>"foo\nbar\nbaz\n");
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"textarea" newline="-"}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals("foo-bar-baz-", "$str");
+
+    $this->{twiki}->{cgiQuery}->param( -name=>'textarea', -value=>"foo\nbar\nbaz\n");
+    $str = $this->{twiki}->handleCommonTags(
+        '%URLPARAM{"textarea" newline=""}%', $this->{test_web}, $this->{test_topic});
+    $this->assert_str_equals("foobarbaz", "$str");
+}
+
+1;
Index: lib/TWiki.pm
===================================================================
--- lib/TWiki.pm	(revision 14505)
+++ lib/TWiki.pm	(working copy)
@@ -3423,12 +3423,13 @@
 sub URLPARAM {
     my( $this, $params ) = @_;
     my $param     = $params->{_DEFAULT} || '';
-    my $newLine   = $params->{newline} || '';
+    my $newLine   = $params->{newline};
     my $encode    = $params->{encode};
     my $multiple  = $params->{multiple};
-    my $separator = $params->{separator} || "\n";
+    my $separator = $params->{separator};
+    $separator="\n" unless (defined $separator);
 
-    my $value = '';
+    my $value;
     if( $this->{cgiQuery} ) {
         if( TWiki::isTrue( $multiple )) {
             my @valueArray = $this->{cgiQuery}->param( $param );
@@ -3447,21 +3448,22 @@
             }
         } else {
             $value = $this->{cgiQuery}->param( $param );
-            $value = '' unless( defined $value );
         }
     }
-    $value =~ s/\r?\n/$newLine/go if( $newLine );
-    if ( $encode ) {
-        if ( $encode =~ /^entit(y|ies)$/i ) {
-            $value = entityEncode( $value );
-        } elsif ( $encode =~ /^quotes?$/i ) {
-            $value =~ s/\"/\\"/go;    # escape quotes with backslash (Bugs:Item3383 fix)
-        } else {
-            $value =~ s/\r*\n\r*/<br \/>/; # Legacy
-            $value = urlEncode( $value );
+    if(defined $value) {
+        $value =~ s/\r?\n/$newLine/go if( defined $newLine );
+        if ( $encode ) {
+            if ( $encode =~ /^entit(y|ies)$/i ) {
+                $value = entityEncode( $value );
+            } elsif ( $encode =~ /^quotes?$/i ) {
+                $value =~ s/\"/\\"/go;    # escape quotes with backslash (Bugs:Item3383 fix)
+            } else {
+                $value =~ s/\r*\n\r*/<br \/>/; # Legacy
+                $value = urlEncode( $value );
+            }
         }
     }
-    unless( $value ) {
+    unless( defined $value ) {
         $value = $params->{default};
         $value = '' unless defined $value;
     }