Add new show command

When configurations use inheritance, it is handy to see the expanded
configuration to get a better feel of what is going to be run. While
Config::Neat already provides a command for this, having a `show`
command helps with the feature being discoverable.

CHANGES

@@ -60,6 +60,8 @@ Revision history
         - When job fails, we now move on to the next job in the config
           (previously the entire config would be skipped)
 
+        - Added new `show` command to display expanded .serge configurations (#40).
+
 1.1     April 20, 2016
 
         - On OS X, expand `~` to the actual `$HOME` path in SQLite DB connection string (#1)

doc/pod/serge-show.pod

@@ -0,0 +1,19 @@
+=head1 NAME
+
+serge-show - Show expanded version of a configuration file
+
+=head1 SYNOPSIS
+
+C<< serge show <configuration-file> >>
+
+Where C<< <configuration-file> >> is a path to a specific .serge file.
+
+=head1 DESCRIPTION
+
+B<serge-show> prints out the interpreted configuration file by applying all
+inheritance rules. This is useful to check the full configuration that will be
+used by Serge.
+
+=head1 SEE ALSO
+
+Part of L<serge> suite.

lib/Serge/Command/show.pm

@@ -0,0 +1,33 @@
+package Serge::Command::show;
+use parent Serge::Command;
+
+use strict;
+
+use Config::Neat::Inheritable;
+use Config::Neat::Render;
+
+sub get_commands {
+    return {
+        show => {
+            handler => \&run,
+            info => 'Show expanded version of a configuration file'
+        },
+    }
+}
+
+sub run {
+    my $config_file = $ARGV[0];
+
+    die "No configuration file specified\n" unless defined $config_file;
+    die "Multiple configuration files not allowed\n" unless $#ARGV == 0;
+
+    my $cfg = Config::Neat::Inheritable->new();
+    my $data = $cfg->parse_file($config_file);
+
+    my $renderer = Config::Neat::Render->new();
+    print $renderer->render($data);
+
+    return 0;
+}
+
+1;