Blacklist certain formats

The %{method} format is probably a bit too 'powerful', so we will not
return an answer if it is included.

We should allow blacklisted formats (as text only), but escape them so they don't
interfere with the actual formats.

lib/DDG/Goodie/RandomDate.pm

@@ -34,12 +34,20 @@ my %standard_queries = (
     'year'                   => ['%Y', 'Year'],
 );
 
+my @blacklist = (
+    '\\%{[^}]*}',
+);
+
+my $blacklist_re = join '|', map { "($_)" } @blacklist;
+
 my $standard_re = join '|', map { "($_)" } (keys %standard_queries);
 
 handle query => sub {
     my $query = shift;
     my $format;
     my $type = 'format';
+    # TODO: Allow blacklisted elements, but escape them for formatting.
+    return if $query =~ /$blacklist_re/;
     if ($query =~ /^random ($standard_re)$/i) {
         my $standard_query = $1;
         my $k = first { $standard_query =~ qr/^$_$/i } (keys %standard_queries);

t/RandomDate.t

@@ -70,9 +70,11 @@ ddg_goodie_test(
     language_test('my', 'random time', 'Time', re($time_12_my), 1),
     language_test('my', 'random day', 'Weekday', re($day_my), 1),
     # Invalid Queries
-    'date for %K'   => undef,
-    'random number' => undef,
-    'example date'  => undef,
+    'date for %K'         => undef,
+    'date for %{year}'    => undef,
+    'date for %Y %{year}' => undef,
+    'random number'       => undef,
+    'example date'        => undef,
 );
 
 done_testing;