From 250428d603130a0764fd66aef77498c8c64cf9c4 Mon Sep 17 00:00:00 2001
From: George Clark <geonwiki@fenachrone.com>
Date: Thu, 2 Apr 2015 11:31:34 -0400
Subject: [PATCH] Item13347: istopic on empty topic name returns true

---
 UnitTestContrib/test/unit/Fn_IF.pm | 11 +++++++++++
 core/lib/Foswiki/If/OP_istopic.pm  |  2 +-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/UnitTestContrib/test/unit/Fn_IF.pm b/UnitTestContrib/test/unit/Fn_IF.pm
index 054033325e..4160db8922 100644
--- a/UnitTestContrib/test/unit/Fn_IF.pm
+++ b/UnitTestContrib/test/unit/Fn_IF.pm
@@ -1175,6 +1175,17 @@ sub test_93b {
     return;
 }
 
+sub test_Item13347 {
+    my $this = shift;
+    $this->simpleTest(
+        test => "istopic ''",
+        then => 0,
+        else => 1
+    );
+
+    return;
+}
+
 sub test_93c {
     my $this = shift;
     $this->simpleTest(
diff --git a/core/lib/Foswiki/If/OP_istopic.pm b/core/lib/Foswiki/If/OP_istopic.pm
index 2adac7a667..888bb01f8d 100644
--- a/core/lib/Foswiki/If/OP_istopic.pm
+++ b/core/lib/Foswiki/If/OP_istopic.pm
@@ -36,7 +36,7 @@ sub evaluate {
         'No context in which to evaluate "' . $a->stringify() . '"' )
       unless $session;
     my ( $web, $topic ) = ( $session->{webName}, $a->_evaluate(@_) );
-    return 0 unless defined $topic;    # null topic cannot possibly exist
+    return 0 unless $topic;    # null/empty topic cannot possibly exist
     ( $web, $topic ) = $session->normalizeWebTopicName( $web, $topic );
     return $session->topicExists( $web, $topic ) ? 1 : 0;
 }