--- /dev/null
+#!/usr/bin/perl
+package IkiWiki;
+
+use warnings;
+use strict;
+use Test::More tests => 5;
+
+BEGIN { use_ok("IkiWiki"); }
+BEGIN { use_ok("IkiWiki::Render"); }
+%config=IkiWiki::defaultconfig();
+$config{srcdir}=$config{destdir}="/dev/null";
+
+%oldrenderedfiles=%pagectime=();
+%pagesources=%pagemtime=%oldlinks=%links=%depends=%typedlinks=%oldtypedlinks=
+%destsources=%renderedfiles=%pagecase=%pagestate=();
+
+IkiWiki::checkconfig();
+
+foreach my $page (qw(tags/a tags/b Reorder Add Remove TypeAdd TypeRemove)) {
+ $pagesources{$page} = "$page.mdwn";
+ $pagemtime{$page} = $pagectime{$page} = 1000000;
+}
+
+$oldlinks{Reorder} = [qw{tags/a tags/b}];
+$links{Reorder} = [qw{tags/b tags/a}];
+
+$oldlinks{Add} = [qw{tags/b}];
+$links{Add} = [qw{tags/a tags/b}];
+
+$oldlinks{Remove} = [qw{tags/a}];
+$links{Remove} = [];
+
+$oldlinks{TypeAdd} = [qw{tags/a tags/b}];
+$links{TypeAdd} = [qw{tags/a tags/b}];
+# This causes TypeAdd to be rebuilt, but isn't a backlink change, so it doesn't
+# cause tags/b to be rebuilt.
+$oldtypedlinks{TypeAdd}{tag} = { "tags/a" => 1 };
+$typedlinks{TypeAdd}{tag} = { "tags/a" => 1, "tags/b" => 1 };
+
+$oldlinks{TypeRemove} = [qw{tags/a tags/b}];
+$links{TypeRemove} = [qw{tags/a tags/b}];
+# This causes TypeRemove to be rebuilt, but isn't a backlink change, so it
+# doesn't cause tags/b to be rebuilt.
+$oldtypedlinks{TypeRemove}{tag} = { "tags/a" => 1 };
+$typedlinks{TypeRemove}{tag} = { "tags/a" => 1, "tags/b" => 1 };
+
+my $oldlink_targets = calculate_old_links([keys %pagesources], []);
+is_deeply($oldlink_targets, {
+ Reorder => { "tags/a" => "tags/a", "tags/b" => "tags/b" },
+ Add => { "tags/b" => "tags/b" },
+ Remove => { "tags/a" => "tags/a" },
+ TypeAdd => { "tags/a" => "tags/a", "tags/b" => "tags/b" },
+ TypeRemove => { "tags/a" => "tags/a", "tags/b" => "tags/b" },
+ });
+my ($backlinkchanged, $linkchangers) = calculate_changed_links([keys %pagesources], [], $oldlink_targets);
+
+is_deeply($backlinkchanged, { "tags/a" => 1 });
+is_deeply($linkchangers, { add => 1, remove => 1, typeadd => 1, typeremove => 1 });