Increase coverage by checking other cases

t/11bar.t

@@ -0,0 +1,9 @@
+use Test::More tests => 1;
+use strict;
+use t::Bar;
+
+my $bar = Regexp::Log::Bar->new;
+my $before =  $bar->{_test};
+my $re = $bar->regexp;
+is( $bar->{_test}, $before + 1, 'postprocessing code executed');
+

t/Bar.pm

@@ -0,0 +1,33 @@
+package Regexp::Log::Bar;
+
+use base qw( Regexp::Log );
+use vars qw( $VERSION %DEFAULT %FORMAT %REGEXP );
+
+$VERSION = 0.01;
+
+# default values
+%DEFAULT = (
+    format  => '%d %c %b',
+    capture => [],
+);
+
+# predefined format strings
+%FORMAT = ( ':default' => '%a %b %c', );
+
+# the regexps that match the various fields
+# this is the difficult part
+%REGEXP = (
+    '%a' => '(?#=a)\\d+(?#!a)',
+    '%b' => '(?#=b)th(?:is|at)(?#!b)',
+    '%c' => '(?#=c)(?#=cs)\\w+(?#!cs)/(?#=cn)\\d+(?#!cn)(?#!c)',
+    '%d' => '(?#=d)(?:foo|bar|baz)(?#!d)',
+);
+
+sub _postprocess {
+    my $self = shift;
+
+    # some code here
+    $self->{_test}++;
+}
+
+1;