diff --git a/multistrap b/multistrap
index 189baaa..a00fbe4 100755
--- a/multistrap
+++ b/multistrap
@@ -1,4 +1,5 @@
 #!/usr/bin/perl
+# vim: tabstop=4:shiftwidth=4:softtabstop=4:expandtab
 
 # Copyright (C) 2009-2015  Neil Williams <codehelp@debian.org>
 # Copyright (C) 2015-2017  Johannes Schauer <josch@mister-muffin.de>
@@ -16,76 +17,60 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+package multistrap;
+
+# This allows one to use this file as an application with main() as the entry
+# point as well as a module to allow unit testing
+__PACKAGE__->main() unless caller();
+
 use strict;
 use warnings;
 use IO::File;
-use Config::Auto;
+use Config::IniFiles;
 use Cwd qw (realpath getcwd);
 use File::Basename;
-use Parse::Debian::Packages;
+use Parse::Debian::Packages; # FIXME: use Dpkg::Index instead
 use POSIX qw(locale_h);
-use Locale::gettext;
+use Dpkg::Gettext;
 use File::Copy;
-
-main();
+use List::Util qw(any all none);
+use Text::Wrap;
+use Getopt::Long;
+use Pod::Usage;
 
 sub main {
-    use vars qw/ @aptsources %packages $str $retries $dir $arch $foreign
-    $unpack $sourcedir @debootstrap %suites %components %sources %keys
-    $preffile $file $tidy $noauth %keyrings $deflist @extrapkgs @includes
-    $setupsh $configsh $omitrequired $omitpreinst @reinstall $tgzname @check
-    $explicit_suite $allow_recommends %omitdebsrc @dsclist %flatfile
-    %important $addimportant @debconf %hooks $warn_count @foreignarches
-    $ignorenative $markauto $default_release/;
-
     setlocale(LC_MESSAGES, "");
     textdomain("multistrap");
     my $progname = basename($0);
-    $default_release = "*";
-    $unpack = "true";
-    %omitdebsrc=();
-    my $dryrun;
-    my $use_shortcut;
-    while( @ARGV ) {
-	    $_= shift( @ARGV );
-	    last if m/^--$/;
-	    if (!/^-/) {
-		    unshift(@ARGV,$_);
-		    last;
-	    } elsif (/^(-\?|-h|--help|--version)$/) {
-		    &usageversion();
-		    exit( 0 );
-	    } elsif (/^(-s|--shortcut)$/) {
-		    $use_shortcut = shift(@ARGV);
-	    } elsif (/^(-f|--file)$/) {
-		    $file = shift(@ARGV);
-	    } elsif (/^(-a|--arch)$/) {
-		    $arch = shift(@ARGV);
-	    } elsif (/^(-d|--dir)$/) {
-		    $dir = shift(@ARGV);
-		    $dir .= ($dir =~ m:/$:) ? '' : "/";
-	    } elsif (/^(--tidy-up)$/) {
-		    $tidy++;
-	    } elsif (/^(--source-dir)$/) {
-		    $sourcedir = shift (@ARGV);
-		    $sourcedir .= ($sourcedir =~ m:/$:) ? '' : "/";
-		    $sourcedir = (-d $sourcedir) ? $sourcedir : undef;
-	    } elsif (/^(--no-auth)$/) {
-		    $noauth++;
-	    } elsif (/^(--dry-run|--simulate)$/) {
-		    $dryrun++;
-	    } else {
-		    die "$progname: "._g("Unknown option")." $_.\n";
-	    }
+
+    my $options = {};
+    # The long option must come before the short option because the first
+    # option will become the key in the $options hash.
+    #
+    # --man is a hidden option (not documented)
+    GetOptions ($options, 'help|h', 'man', 'simulate|dry-run', 'shortcut|s=s',
+        'file|f=s', 'arch|a=s', 'directory|d=s', 'tidy-up!', 'source-dir=s', 'auth!'
+    ) or pod2usage(2);
+    pod2usage(1) if ($options->{help});
+    pod2usage(-exitval => 0, -verbose => 2) if ($options->{man});
+    pod2usage(-message => "Mandatory argument -f or --file is missing.\n",
+        -exitval => 1, -verbose => 1) if (! exists $options->{file});
+
+    if (exists $options->{shortcut} && exists $options->{file}) {
+        die (_g("Options --shortcut and --file are mutually exclusive\n"));
     }
-    if (defined $use_shortcut) {
-	    my $short = "/usr/share/multistrap/".$use_shortcut.".conf";
-	    $file = $short if (-f $short);
-	    $short = "/etc/multistrap.d/".$use_shortcut.".conf";
-	    $file = $short if (-f $short);
+
+    my $file;
+    if (exists $options->{shortcut} && defined $options->{shortcut}) {
+        # FIXME: use ~/.config/multistrap and XDG paths as well
+        my $short = "/usr/share/multistrap/".$options->{shortcut}.".conf";
+        $file = $short if (-f $short);
+        $short = "/etc/multistrap.d/".$options->{shortcut}.".conf";
+        $file = $short if (-f $short);
+    } elsif (exists $options->{file} && defined $options->{file}) {
     }
     if (not defined $file) {
-	die (sprintf (_g("Need a configuration file - use %s -f\n"), $progname));
+        die (sprintf (_g("Need a configuration file - use %s -f\n"), $progname));
     }
 
     my $cachedir = "var/cache/apt/"; # archives
@@ -93,38 +78,51 @@ sub main {
     my $etcdir = "etc/apt/";         # sources
     my $dpkgdir = "var/lib/dpkg/";   # state
 
-    my $cfgdir=dirname($file);
-    cascade($file);
+    # The "config" is read from configuration files.
+    # The "options" come from the command line.
+    # The "settings" are the config and options together.
+    my $config_tree = parse_ini($file);
+    my $config = get_config_from_tree($config_tree);
+    my $settings = resolve_settings();
+    # Overwrite settings from the configuration file with settings from the
+    # command line
+    if (exists $options->{arch}) {
+        $settings->{general}{arch} = $options->{arch};
+    }
+    if (exists $options->{directory}) {
+        $settings->{general}{directory} = $options->{directory};
+    }
+    if (exists $options->{'tidy-up'}) {
+        $settings->{general}{cleanup} = $options->{'tidy-up'};
+    }
+    if (exists $options->{'source-dir'}) {
+        $settings->{general}{retainsources} = $options->{'source-dir'};
+    }
+    if (exists $options->{auth}) {
+        $settings->{general}{noauth} = !$options->{auth};
+    }
 # Translators: fields are programname, include file.
-    printf (_g("%s using %s\n"), $progname, $file);
     my $host = `dpkg --print-architecture`;
     chomp($host);
-    foreach my $inc (@includes) {
-	    cascade($inc);
+    if ($settings->{general}{omitrequired} and $settings->{general}{addimportant}) {
+        warn("\n"._g("Error: Cannot set 'add Priority: important' when packages ".
+                "of 'Priority: required' are being omitted.\n"));
+        if (defined $options->{simulate}) {
+            warn("\n");
+            &dump_settings;
+            exit 0;
+        }
+        exit (7);
     }
-    if (defined $omitrequired and defined $addimportant) {
-	    warn("\n"._g("Error: Cannot set 'add Priority: important' when packages ".
-	    "of 'Priority: required' are being omitted.\n"));
-	    if (scalar @includes > 0) {
-		    my $plural = ngettext("Please also check the included configuration file:",
-		    "Please also check the included configuration files:", scalar @includes);
-		    warn (sprintf("%s '%s'\n", $plural, join ("', '", sort @includes)));
-	    }
-	    if (defined $dryrun) {
-		    warn("\n");
-		    &dump_config;
-		    exit 0;
-	    }
-	    exit (7);
-    }
-    uniq_sort (\@debootstrap);
-    uniq_sort (\@aptsources);
-    if (defined $dryrun) {
-	    &dump_config;
-	    exit 0;
+    if (defined $options->{simulate}) {
+        &dump_settings;
+        exit 0;
     }
+    my @debootstrap = uniq_sort (@{$settings->{general}{debootstrap}}, @{$settings->{general}{bootstrap}});
+    my @aptsources = uniq_sort (@{$settings->{general}{aptsources}});
 # Translators: fields are: programname, configfile.
     printf (_g("%s using %s\n"), $progname, $file);
+    my $arch = $settings->{general}{arch};
     if ((not defined $arch) or ($arch eq "")) {
 	    $arch = $host;
 	    printf (_g("Defaulting architecture to native: %s\n"),$arch);
@@ -133,9 +131,11 @@ sub main {
     } else {
 	    printf (_g("Using foreign architecture: %s\n"), $arch);
     }
-    $foreign++ if (($host ne $arch) or (defined $ignorenative));
+    my $foreign;
+    $foreign++ if (($host ne $arch) or ($settings->{general}{ignorenative}));
+    my $dir = $settings->{general}{directory};
     if (not defined $dir or not defined $arch) {
-	    &dump_config;
+	    &dump_settings;
 	    exit 3;
     }
     unless (keys %sources) {
@@ -261,6 +261,7 @@ sub main {
 	    }
     }
     my $k;
+    # FIXME: remove duplicates from %keyrings
     foreach my $pkg (values %keyrings) {
 	    next if (not defined $pkg);
 	    next if ("" eq "$pkg");
@@ -291,6 +292,8 @@ sub main {
 			    File::Copy::copy "${xdir}/usr/share/keyrings/${gpg}", "${dir}${etcdir}trusted.gpg.d/";
 		    }
 		    system ("rm -rf ${xdir}");
+		    # FIXME: if the globbing was too aggressive, then this
+		    # will remove files that are needed later
 		    unlink ($file);
 	    }
     }
@@ -320,7 +323,7 @@ sub main {
     $config_str .= " -o Dir::Etc=" . shellescape("${dir}${etcdir}");
     $config_str .= " -o Dir::Etc::Parts=" . shellescape("${dir}${etcdir}apt.conf.d/");
     $config_str .= " -o Dir::Etc::PreferencesParts=" . shellescape("${dir}${etcdir}preferences.d/");
-    $config_str .= " -o APT::Default-Release=" . shellescape($default_release);
+    $config_str .= " -o APT::Default-Release=" . shellescape($default_release) if (defined $default_release);
 #	if (not defined $preffile);
     if (defined $deflist) {
 	    my $sourcesname = "sources.list.d/multistrap.sources.list";
@@ -377,7 +380,7 @@ sub main {
     }
     chomp($str);
     @s = split (/ /, $str);
-    uniq_sort (\@s);
+    @s = uniq_sort (@s);
     $str = join (' ', @s);
     print "$apt_get -y install $str\n";
     $retval = 0;
@@ -898,7 +901,7 @@ sub handle_source_packages {
 			}
 		}
 	}
-	uniq_sort (\@dsclist);
+	@dsclist = uniq_sort (@dsclist);
 	my $olddir = getcwd();
 	chdir ($sourcedir);
 	if (scalar @dsclist > 0) {
@@ -1151,179 +1154,490 @@ will be created - it is not packed into a .tgz once complete.
 	or die ("$progname: ". _g("failed to write usage:") . "$!\n");
 }
 
-sub cascade {
-	$file = shift;
-	my @req_arches=();
-	my $config = Config::Auto::parse($file, format => 'ini');
-	if (not defined $config or (scalar keys %$config) == 0) {
-	    my $progname = basename($0);
-		die ("$progname: ". sprintf(_g("Failed to parse '%s'!\n"), $file));
-	}
-	my $type;
-	my $value;
-	foreach my $key (%$config) {
-		$type = lc($key) if (ref $key ne "HASH");
-		$value = $key if (ref $key eq "HASH");
-		$keys{$type} = $value;
-	}
-	foreach my $section (sort keys %keys) {
-		if ($section eq "general") {
-			$arch = $keys{$section}{'arch'}
-				if (defined $keys{$section}{'arch'} and (not defined $arch));
-			$dir = $keys{$section}{'directory'}
-				if (defined $keys{$section}{'directory'} and (not defined $dir));
-			# support the original value but replace by new value.
-			$unpack = "false" if (defined $keys{$section}{'forceunpack'} and (lc($keys{$section}{'forceunpack'}) ne "true"));
-			$unpack = "false" if (defined $keys{$section}{'unpack'} and (lc($keys{$section}{'unpack'} ne "true")));
-			$markauto++ if ((defined $keys{$section}{'markauto'}) and (lc($keys{$section}{'markauto'}) eq "true"));
-			$configsh = $keys{$section}{'configscript'}
-				if (defined $keys{$section}{'configscript'} and (not defined $configsh));
-			$tgzname = $keys{$section}{'tarballname'}
-				if (defined $keys{$section}{'tarballname'} and (not defined $tgzname));
-			chomp($tgzname) if (defined $tgzname);
-			undef $tgzname if (defined $tgzname and $tgzname eq '');
-			if ((defined $configsh) and ($configsh eq '')) {
-				undef $configsh
-			}
-			if ((defined $configsh) and (not -x $configsh)) {
-				my $configmsg = sprintf (_g("INF: '%s' exists but is not executable - ignoring.\n"), $configsh);
-				undef $configsh;
-				warn $configmsg;
-				$warn_count++;
-			}
-			$setupsh = $keys{$section}{'setupscript'}
-				if (defined $keys{$section}{'setupscript'} and (not defined $setupsh));
-			undef $setupsh if ((defined $setupsh) and (not -x $setupsh));
-			$omitrequired++ if (defined $keys{$section}{'omitrequired'} and (lc($keys{$section}{'omitrequired'}) eq "true"));
-			$addimportant++ if (defined $keys{$section}{'addimportant'} and (lc($keys{$section}{'addimportant'}) eq "true"));
-			$omitpreinst++ if (defined $keys{$section}{'omitpreinst'} and ($keys{$section}{'omitpreinst'} eq "true"));
-			$tidy++ if ((defined $keys{$section}{'cleanup'}) and ($keys{$section}{'cleanup'} eq "true"));
-			$noauth++ if ((defined $keys{$section}{'noauth'}) and ($keys{$section}{'noauth'} eq "true"));
-			$ignorenative++ if ((defined $keys{$section}{'ignorenativearch'}) and
-				(lc($keys{$section}{'ignorenativearch'}) eq 'true'));
-			$preffile = $keys{$section}{'aptpreferences'}
-				if (defined $keys{$section}{'aptpreferences'} and (not defined $preffile));
-			undef $preffile if ((defined $preffile) and (not -f $preffile));
-			$sourcedir = $keys{$section}{'retainsources'}
-				if ((defined $keys{$section}{'retainsources'}) and (-d $keys{$section}{'retainsources'}));
-			$explicit_suite++ if ((defined $keys{$section}{'explicitsuite'}) and
-				($keys{$section}{'explicitsuite'} eq "true"));
-			$allow_recommends++ if ((defined $keys{$section}{'allowrecommends'}) and
-				($keys{$section}{'allowrecommends'} eq "true"));
-			$default_release = $keys{$section}{'aptdefaultrelease'}
-				if (defined $keys{$section}{'aptdefaultrelease'});
-			my @p = split(' ', $keys{$section}{'debconfseed'})
-				if (defined $keys{$section}{'debconfseed'});
-			foreach my $f (@p) {
-				my $fl = realpath ($f);
-				next if ($fl eq "");
-				next if (not -f $fl);
-				chomp ($fl);
-				push @debconf, $fl;
-			}
-			my @h = split(' ', $keys{$section}{'hookdir'})
-				if (defined $keys{$section}{'hookdir'});
-			foreach my $f (@h) {
-				opendir (HOOKS, "$f") or next;
-				my @hookfiles=grep(!m:\.\.?$:, readdir HOOKS);
-				closedir(HOOKS);
-				foreach my $hf (@hookfiles) {
-					my $fl = realpath ("$f/$hf");
-					next if (($fl eq "") or (not -f $fl) or (not -x $fl));
-					push (@{$hooks{'A'}}, $fl) if ($hf =~ /^completion/);
-					push (@{$hooks{'D'}}, $fl) if ($hf =~ /^download/);
-					push (@{$hooks{'N'}}, $fl) if ($hf =~ /^native/);
-				}
-			}
-			my @ma = split(' ',$keys{$section}{'multiarch'})
-			if (defined $keys{$section}{'multiarch'});
-			push @foreignarches, @ma;
-			my @d=();
-			@d = split(' ', lc($keys{$section}{'debootstrap'}))
-				if (defined $keys{$section}{'debootstrap'});
-			push @debootstrap, @d;
-			my @b = split(' ', lc($keys{$section}{'bootstrap'}))
-				if (defined $keys{$section}{'bootstrap'});
-			push @debootstrap, @b;
-			my @a=();
-			if (exists $keys{$section}{'aptsources'}) {
-				@a = split (' ', lc($keys{$section}{'aptsources'}));
-			}
-			push @aptsources, @a;
-			my @i = split (' ', $keys{$section}{'include'})
-				if (defined $keys{$section}{'include'});
-			foreach my $inc (@i) {
-				# look for the full filepath or try same directory as current conf.
-				if (not -f $inc) {
-				    my $cfgdir=dirname($file);
-					my $chk = realpath ("$cfgdir/$inc");
-					chomp ($chk) if (defined $chk);
-					$inc = $chk if (-f $chk);
-				}
-				if (not -f $inc) {
-					my $dirmsg = sprintf (_g("ERR: Cannot find include file: '%s' for '%s'"), $inc, $file);
-					die ("$dirmsg\n");
-				}
-			}
-			push @includes, @i;
-		} else {
-			$sources{$section}=$keys{$section}{'source'};
-			# don't set suite or component if URL is of apt-ftparchive trailing-slash form
-			# regexp is: optional string in '[]', string without '[' or ']', string ending in '/'
-			$flatfile{$section}++ if (($sources{$section} =~ /^(\[.*\] )*[^\[\]]+ .+\/$/));
-			if ((exists $keys{$section}{'architecture'}) and
-				($keys{$section}{'architecture'} ne "")) {
-				my $frgn_arch = $keys{$section}{'architecture'};
-				my @tmp=();
-				if (ref ($keys{$section}{'packages'}) eq 'ARRAY') {
-					foreach my $p (@{$keys{$section}{'packages'}}) {
-						push @tmp, "$p:$frgn_arch";
-						push @req_arches, $frgn_arch;
-					}
-				} else {
-					foreach my $p (split(' ', $keys{$section}{'packages'})) {
-						push @tmp, "$p:$frgn_arch";
-						push @req_arches, $frgn_arch;
-					}
-				}
-				$packages{$section} = join(' ', @tmp);
-			} else {
-				if (ref ($keys{$section}{'packages'}) eq 'ARRAY') {
-					$packages{$section}=join(' ', @{$keys{$section}{'packages'}});
-				} else {
-					$packages{$section}=join(' ', $keys{$section}{'packages'});
-				}
-			}
-			$suites{$section}=$keys{$section}{'suite'}
-				if (not exists $suites{$section} and not exists $flatfile{$section});
-			$components{$section}=$keys{$section}{'components'}
-				if (not exists $components{$section} and not exists $flatfile{$section});
-			$omitdebsrc{$section}=$section if ((defined $keys{$section}{'omitdebsrc'})
-				and ($keys{$section}{'omitdebsrc'} eq "true"));
-			push @reinstall, split (/ /, $keys{$section}{'reinstall'})
-				if (defined $keys{$section}{'reinstall'});
-			$components{$section}='main' if (not defined $components{$section});
-			$keyrings{$section}=$keys{$section}{'keyring'} if (not exists $keyrings{$section});
-			push @extrapkgs, split (' ', $keys{$section}{'additional'})
-				if (defined $keys{$section}{'additional'});
-		}
-	}
-	my %archchk=();
-	foreach my $farch (@foreignarches) {
-		$archchk{$farch}++;
-	}
-	foreach my $req (@req_arches) {
-		if (not exists $archchk{$req}) {
-			# Translators: %1 and %2 are the same value here - the erroneous architecture name
-			my $reqmsg = sprintf (_g("ERR: Misconfiguration in: 'architecture' option. ".
-			"Packages of architecture=%s requested but '%s' is not included in the multiarch=".
-			join (" ", @foreignarches) . " option.\n"), $req, $req);
-			warn $reqmsg;
-			die ("\n");
-		}
-	}
-	uniq_sort (\@reinstall);
-	uniq_sort (\@extrapkgs);
+my $general_spec = {
+    arch => {
+        type => 'string',
+        help => 'Native architecture'},
+    directory => {
+        type => 'string',
+        help => 'Output directory'
+    },
+    cleanup => {
+        type => 'bool',
+        default => 1,
+        help => 'remove apt cache data'
+    },
+    noauth => {
+        type => 'bool',
+        default => 0,
+        help => 'Allow the use of unauthenticated repositories'
+    },
+    unpack => {
+        type => 'bool',
+        default => 1,
+        help => 'Extract all downloaded archives'
+    },
+    explicitsuite => {
+        type => 'bool',
+        default => 0,
+        help => 'Suite explicitly selected instead of using latest versions.'
+    },
+    aptsources => {
+        type => 'section',
+        list => 1,
+        help => ''
+    },
+    bootstrap => {
+        type => 'section',
+        list => 1,
+        help => ''
+    },
+    omitrequired => {
+        type => 'bool',
+        default => 0,
+        help => ''
+    },
+    addimportant => {
+        type => 'bool',
+        default => 0,
+        help => ''
+    },
+    debootstrap => {
+        type => 'section',
+        list => 1,
+        default => [],
+        help => ''
+    },
+    bootstrap => {
+        type => 'section',
+        list => 1,
+        default => [],
+        help => ''
+    },
+    ignorenative => {
+        type => 'bool',
+        default => 0,
+        help => ''
+    },
+    retainsources => {
+        type => 'string',
+        help => ''
+    },
+};
+
+my $section_spec = {
+    packages => {
+        type => 'stringlist',
+        list => 1,
+        default => [],
+        help => ''
+    },
+    source => {
+        type => 'string',
+        list => 1,
+        help => ''
+    },
+    keyring => {
+        type => 'string',
+        list => 1,
+        default => [],
+        help => ''
+    },
+    suite => {
+        type => 'string',
+        help => ''
+    },
+    omitdebsrc => {
+        type => 'bool',
+        default => 0,
+        help => ''
+    },
+};
+
+sub get_inclduegraph_from_tree {
+    my $config_tree = shift;
+
+    if (!exists $config_tree->{general}{include}) {
+        return [];
+    }
+    # Traverse the tree in depth-first-search order.
+    #
+    # If the same file occurs in multiple branches of the tree, then the
+    # resulting graph will be a directed acyclic graph and not a tree
+    # anymore.
+    my $includegraph = [];
+    sub visit {
+        my $acc = shift;
+        my $n = shift;
+        # The origin of the includes in this file must exactly be one file
+        # and not the result of a merge of two or more files.
+        if (scalar @{$n->[2]} != 1) {
+            die "Include statements were merged but that is forbidden";
+        }
+        # Add an edge from the filename of this node to all files that it
+        # included.
+        my $f = $n->[2]->[0];
+        for my $i (@{$n->[0]}) {
+            # Make the filename absolute instead of relative to the
+            # current file
+            push @{$acc}, [$f, dirname($f) . '/' . $i];
+        }
+        # Recurse.
+        for my $c (@{$n->[1]}) {
+            visit($acc, $c);
+        }
+    };
+    visit($includegraph, $config_tree->{general}{include});
+    return $includegraph;
+}
+
+sub get_config_from_tree {
+    my $config_tree = shift;
+
+    my $config = {};
+    foreach my $section (keys %{$config_tree}) {
+        my $spec;
+        if ($section eq "general") {
+            $spec = $general_spec;
+        } else {
+            $spec = $section_spec;
+        }
+        # First fill the default with the configuration from the spec.
+        while (my ($k, $v) = each %{$spec}) {
+            # Do not set values from the spec that do not have a default
+            if (! exists $v->{default}) {
+                next;
+            }
+            $config->{$section}{$k} = $v->{default};
+        }
+        # Then overwrite the default values with what was read from the config.
+        while (my ($k, $v) = each %{$config_tree->{$section}}) {
+            if (! exists $spec->{$k}) {
+                printf("unknown property: $k\n");
+                next;
+            }
+            # The "include" parameter of the "general" section is the only one
+            # where we are interested in more values than from the root node of
+            # the config tree. We do not handle it here.
+            if ($section eq 'general' && $k eq 'include') {
+                next;
+            }
+            # Make sure that non-list-type values contain no more than one element
+            if (scalar @{$v->[0]} > 1 && $spec->{$k}{list} != 1) {
+                die "property $k must not be a list";
+            }
+            my @value;
+            # Convert and validate config settings.
+            if ($spec->{$k}{type} eq 'string') {
+                @value = @{$v->[0]};
+            } elsif ($spec->{$k}{type} eq 'bool') {
+                my @valid_bool = ('true', 'false', 'yes', 'no', '1', '0');
+                # Check if the given value can be interpreted as a boolean.
+                foreach my $b (@{$v->[0]}) {
+                    if (none {lc($b) eq $_} @valid_bool) {
+                        die "property $k is not a valid boolean";
+                    }
+                }
+                # Check if the given value evaluates to true.
+                sub is_true {
+                    my $s = shift;
+                    return any { $s eq $_ } ('true', 'yes', '1');
+                }
+                @value = map { is_true(lc($_)) } @{$v->[0]};
+            } elsif ($spec->{$k}{type} eq 'section') {
+                # Check if the given section name matches an existing section.
+                foreach my $s (@{$v->[0]}) {
+                    foreach my $t (split /\s+/, $s) {
+                        if (lc($t) eq "general") {
+                            die "section name $t forbidden";
+                        }
+                        if (! exists $config_tree->{lc($t)}) {
+                            die "case-insensitive section name $t not found";
+                        }
+                    }
+                }
+                @value = map { lc } (map { split /\s+/ } @{$v->[0]});
+            } elsif ($spec->{$k}{type} eq 'stringlist') {
+                @value = map { split /\s+/ } @{$v->[0]};
+            } else {
+                die "invalid type: $spec->{$k}{type}";
+            }
+            if (exists $spec->{$k}{list} && $spec->{$k}{list} == 1) {
+                # If this is a list-type value, store it as an array reference
+                $config->{$section}{$k} = [@value];
+            } else {
+                # If this is a non-list value, store its first (and only) value as
+                # a simple scalar
+                $config->{$section}{$k} = $value[0];
+            }
+        }
+    }
+    return $config;
+}
+
+# Write a representation of the include graph in dot format to standard output
+sub dump_includegraph {
+    my $includegraph = shift;
+
+    print "digraph g {\n";
+    my %mapping = ();
+    my $num_verts = 0;
+    foreach my $e (@{$includegraph}) {
+        my ($v1, $v2) = @{$e};
+        if (! exists $mapping{$v1}) {
+            $mapping{$v1} = $num_verts;
+            $num_verts += 1;
+        }
+        if (! exists $mapping{$v2}) {
+            $mapping{$v2} = $num_verts;
+            $num_verts += 1;
+        }
+    }
+    foreach my $v (sort keys %mapping) {
+        my $i = $mapping{$v};
+        print "    $i [label=\"$v\"];\n";
+    }
+    foreach my $e (@{$includegraph}) {
+        my ($v1, $v2) = @{$e};
+        my $i1 = $mapping{$v1};
+        my $i2 = $mapping{$v2};
+        print "    $i1 -> $i2;\n";
+    }
+    print "}\n";
+    return $includegraph;
+}
+
+sub dump_settings {
+    my $settings = shift;
+
+    # Get a representation of the configuration sections such that the
+    # "general" section comes first and is followed by the others in sorted
+    # order.
+    my @sections = sort grep !/^general$/ (keys %{$settings})
+    if (exists $settings->{general}) {
+        unshift @sections, "general";
+    }
+
+    sub value_formatter {
+        my $val = shift;
+        my $type = shift;
+        if ($type eq "bool") {
+            if ($val) {
+                return "true";
+            } else {
+                return "false";
+            }
+        } elsif ($type eq "section") {
+            return lc($val);
+        } elsif ($type eq "stringlist") {
+            return join " ", @{$val};
+        } else {
+            return $val;
+        }
+    };
+
+    foreach my $section (@sections) {
+        my $spec;
+        if ($section eq "general") {
+            $spec = $general_spec;
+        } else {
+            $spec = $section_spec;
+        }
+        print("[$section]\n");
+        foreach my $k (sort keys %{$settings->{$section}}) {
+            my $v = $settings->{$section}{$k};
+            my $type = $spec->{$k}{type};
+            my $t = $spec->{$k}{help};
+            if (exists $spec->{$k}{default}) {
+                $t .= " (default: ";
+                $t .= value_formatter($spec->{$k}{default}, $type);
+                $t .= ")";
+            }
+            $t .= "\n";
+            print(wrap('# ', '# ', $t));
+            if (ref $v eq 'ARRAY') {
+                foreach my $e (@{$v}) {
+                    print("$k=" . value_formatter($e, $type) . "\n");
+                }
+            } else {
+                print("$k=" . value_formatter($v, $type) . "\n");
+            }
+        }
+    }
+}
+
+# Given a config.ini, recursively traverses all included ini files and returns
+# a hash which represents a merge of the included ini file tree.
+#
+# Note, that the resulting data structure will even be a tree if the same ini
+# is included by multiple siblings.
+#
+# The first argument is the ini file to parse.
+#
+# To prevent cycles, the remaining arguments are the set of ini files that
+# make the path of the current config to the root to prevent cycles.
+#
+# The merging is done such that all configuration values that are specified in
+# more than one descendant, are represented as nested array refs representing
+# the transitive reduction of the configuration file tree that they appeared
+# in. We don't use nested hash refs because those would not remain in order.
+#
+# Nodes in the tree are represented as tuples (array refs) where the first
+# element is the list of values stored in the current node and the second
+# element is its list of children.
+#
+# Example:
+#
+# complex.ini:
+# [general]
+# include=blub.ini
+# include=bla.ini
+# property=1
+#
+# branch1.ini:
+# [general]
+# include=shared.ini
+# property=2
+#
+# branch2.ini
+# [general]
+# include=intermediate.ini
+# property=3
+#
+# intermediate.ini
+# [general]
+# include=shared.ini
+# foo=bar
+#
+# shared.ini
+# [general]
+# property=4
+#
+# Result:
+#
+# my %config = {
+#     general => {
+#         include => [
+#             [ 'branch1.ini', 'branch2.ini' ],
+#             [
+#                 [ ['shared.ini'], [] ],
+#                 [ ['intermediate.ini'], [
+#                     [ ['shared.ini'], [] ]
+#                 ] ]
+#             ]
+#         ],
+#         property => [
+#             [ '1' ],
+#             [
+#                 [ ['2'], [ [ [ '4' ], [] ] ] ],
+#                 [ ['3'], [ [ [ '4' ], [] ] ] ],
+#             ]
+#         ],
+#         foo => [ [ 'bar' ], [] ]
+#     }
+# }
+#
+# Observations:
+#
+#  - The full include tree is seen in $config{'global'}{'include'}.
+#  - Part of the tree is seen in $config{'global'}{'property'}. There is no
+#    "node" for intermediate.ini because it didn't contain the property.
+#  - $config{'global'}{'foo'} is a simple scalar because it only occurred once
+sub parse_ini {
+    my $file = shift;
+    my @seen_includes = @_;
+    # if this is the first call, then seen_includes might be empty. Then
+    # add ourselves
+    if (scalar @seen_includes == 0) {
+        @seen_includes = ($file);
+    }
+    my $progname = basename($0);
+    printf STDERR (_g("%s using %s\n"), $progname, $file);
+    tie (my %ini, 'Config::IniFiles', (
+            -file => $file,
+            -nocase => 1,
+            -allowedcommentchars => '#',
+            -handle_trailing_comment => 1))
+    || die sprintf(_g("Failed to parse '%s'!\n"), $file);
+    # Go through all included configs, parse them and put the values from
+    # the results into the SECOND tuple element (the children of this
+    # config)
+    my $config;
+    if (exists $ini{'general'}{'include'}) {
+        my @includes;
+        if (ref ($ini{'general'}{'include'}) eq 'ARRAY') {
+            @includes = @{$ini{'general'}{'include'}};
+        } else {
+            @includes = ($ini{'general'}{'include'});
+        }
+        foreach my $include (@includes) {
+            if (any { $_ eq $include } @seen_includes) {
+                die "$include was included already. Cyclic or duplicate includes detected.";
+            }
+            my $newini = parse_ini(dirname($file).'/'.$include, uniq_sort(@seen_includes, $include));
+            # merge this configuration into the ones that were read so far
+            foreach my $section (keys %{$newini}) {
+                # FIXME: we would like to use "each" but there is
+                # #849298
+                foreach my $parameter (keys %{$newini->{$section}}) {
+                    my $value = $newini->{$section}{$parameter};
+                    if (exists $config->{$section}{$parameter}) {
+                        push @{$config->{$section}{$parameter}[1]}, $value;
+                        push @{$config->{$section}{$parameter}[2]}, $include;
+                    } else {
+                        # parameter doesn't exist, so just copy it
+                        $config->{$section}{$parameter} = [ undef, [$value], [$include] ];
+                    }
+                }
+            }
+        }
+    }
+    # Go through this config and put the read values into the FIRST tuple
+    # element
+    foreach my $section (keys %ini) {
+        foreach my $parameter (keys %{$ini{$section}}) {
+            my $value = $ini{$section}{$parameter};
+            if (ref $value ne 'ARRAY') {
+                $value = [$value];
+            }
+            if (exists $config->{$section}{$parameter}) {
+                $config->{$section}{$parameter}[0] = $value;
+                $config->{$section}{$parameter}[2] = [$file];
+            } else {
+                $config->{$section}{$parameter} = [ $value, [], [$file] ];
+            }
+        }
+    }
+    # Go through all config parameters at this level (we don't recurse
+    # here) and apply a transformation on nodes that were not filled by
+    # this config file
+    foreach my $section (keys %{$config}) {
+        foreach my $parameter (keys %{$config->{$section}}) {
+            my $value = $config->{$section}{$parameter};
+            # only operate on this node if its value is not set
+            if (defined $value->[0]) {
+                next;
+            }
+            if (scalar @{$value->[1]} == 1) {
+                # if this node only has a single child, replace this node
+                # by the child
+                $config->{$section}{$parameter} = $value->[1]->[0];
+            } else {
+                # concatenate the values of all leave nodes to the value of
+                # this node
+                my @leaves = grep {scalar @{$_->[1]} == 0} @{$value->[1]};
+                my @nonleaves = grep {scalar @{$_->[1]} != 0} @{$value->[1]};
+                $config->{$section}{$parameter} = [
+                    # make sure to dereference the leave values so
+                    # that we do not get a nested list
+                    [map({@{$_->[0]}} @leaves)],
+                    [@nonleaves],
+                    [map({@{$_->[2]}} @leaves)]
+                ]
+            }
+        }
+    }
+    return $config;
 }
 
 sub system_fatal {
@@ -1347,186 +1661,86 @@ sub mkdir_fatal {
 	}
 }
 
-sub _g {
-	return gettext(shift);
-}
-
 sub uniq_sort {
-	my $aryref = shift;
-	my %uniq = ();
-	foreach my $i (@$aryref) {
-		$uniq{$i}++;
-	}
-	@$aryref = sort keys %uniq;
+    my %uniq;
+    @uniq{@_} = ();
+    return sort keys %uniq;
 }
 
-sub dump_config {
-	my $msg;
-	if (not defined $dir or not defined $arch) {
-		$msg = sprintf(_g("The supplied configuration file '%s'".
-		" cannot be parsed correctly."), $file);
-		warn ("\n$msg\n\n");
-	}
-	my $plural;
-	@check=();
-	push @check, @debootstrap;
-	push @check, @aptsources;
-	uniq_sort (\@check);
-	foreach my $sect (@check) {
-		if (not exists $keys{$sect}) {
-			$msg .= sprintf (_g("ERR: The '%s' section is not defined.\n"), $sect);
-		}
-	}
-	if (scalar @includes > 0) {
-		$plural = ngettext("Including configuration file from:",
-		"Including configuration files from:", scalar @includes);
-		printf ("include:\t%s '%s'\n", $plural, join ("', '", sort @includes));
-	} else {
-		printf ("include:\t\t"._g("No included configuration files.\n"));
-	}
-	undef $plural;
-	print "\n";
-	# explain the bootstrap section details explicitly and just refer to
-	# those for the apt sources.
-	foreach my $sect_name (@check) {
-		next unless (defined $packages{$sect_name});
-		printf ("Section name:\t$sect_name\n");
-		print "\tsource:\t\t$sources{$sect_name}\n";
-		my @sorted = split(/ /, $packages{$sect_name});
-		uniq_sort (\@sorted);
-		print "\tsuite:\t\t$suites{$sect_name}\n" if (not exists $flatfile{$sect_name});
-		print "\tcomponents:\t$components{$sect_name}\n" if (not exists $flatfile{$sect_name});
-		# only list packages in a bootstrapping section
-		if (not grep(/^$sect_name$/i, @debootstrap)) {
-			printf ("\t%s\n",_g("Not listed as a 'Bootstrap' section."));
-			print "\n";
-			next;
-		}
-		print "\tpackages:\t".join(" ", @sorted)."\n";
-		print "\n";
-	}
-	$plural = ngettext("Section to install", "Sections to install", scalar @debootstrap);
-	printf ("%s:\t%s\n", $plural, join(" ", sort @debootstrap));
-	$plural = ngettext("Section for updates", "Sections for updates", scalar @aptsources);
-	printf ("%s:\t%s\n", $plural, join(" ", sort @aptsources));
-	my @srcdump=();
-	foreach my $src (sort keys %sources) {
-		next if ((!grep(/^$src$/i, @aptsources)) or (!grep(/^$src$/i, @debootstrap)));
-		push @srcdump, $sources{$src};
-	}
-	my $srcmsg="omitdebsrc\t\t"._g("Omit deb-src from sources.list for sections:");
-	if (scalar keys %omitdebsrc == 0) {
-		$srcmsg .= sprintf(" %s",_g("None."));
-	} else {
-		foreach my $omit (sort keys %omitdebsrc) {
-			$srcmsg .= " " . $omitdebsrc{$omit} if (defined $omitdebsrc{$omit});
-		}
-	}
-	print "$srcmsg\n";
-	if (defined $explicit_suite) {
-		printf("explicitsuite:\t\t"._g("Explicit suite selection: Yes\n"));
-	} else {
-		printf("explicitsuite:\t\t"._g("Explicit suite selection: No - let apt use latest.\n"));
-	}
-	if (defined $allow_recommends) {
-		printf("allowrecommends:\t"._g("Recommended packages are added to the selection.\n"));
-	} else {
-		printf("allowrecommends:\t"._g("Recommended packages are ignored.\n"));
-	}
-	if ($default_release ne "*") {
-		printf("aptdefaultrelease:\t"."APT::Default-Release: ".$default_release."\n");
-	}
-	if (defined $markauto) {
-		printf("markauto:\t\t"._g("Marking dependency packages as auto-installed.\n"));
-	}
-	$plural = ngettext("Debconf preseed file", "Debconf preseed files", scalar @debconf);
-	printf("%s:\t%s\n", $plural, join(" ", sort @debconf)) if (scalar @debconf > 0);
-	if (defined ($hooks{'D'} and scalar @{$hooks{'D'}} > 0)) {
-		# Translators: leaving the plural blank to keep the lines shorter.
-		$plural = ngettext ("Download hook: ", "", scalar @{$hooks{'D'}});
-		print "download hooks:\t\t$plural".join (", ", sort @{$hooks{'D'}})."\n";
-	}
-	if (defined ($hooks{'N'} and scalar @{$hooks{'N'}} > 0)) {
-		# Translators: leaving the plural blank to keep the lines shorter.
-		$plural = ngettext ("Native hook: ", "", scalar @{$hooks{'N'}});
-		print "native hooks:\t\t$plural".join (", ", sort @{$hooks{'N'}})."\n";
-	}
-	if (defined ($hooks{'A'} and scalar @{$hooks{'A'}} > 0)) {
-		# Translators: leaving the plural blank to keep the lines shorter.
-		$plural = ngettext ("Completion hook: ", "", scalar @{$hooks{'A'}});
-		print "completion hooks:\t$plural".join (", ", sort @{$hooks{'A'}})."\n";
-	}
-	$plural = ngettext ("Extra Package: ", "Extra Packages: ", scalar @extrapkgs);
-	print "additional:\t\t$plural".join (", ", sort @extrapkgs)."\n" if (scalar @extrapkgs > 0);
-	print "reinstall:\t\t".join (", ", sort (@reinstall))."\n" if (scalar @reinstall > 0);
-	if (defined $arch and $arch ne "") {
-		printf ("Architecture:\t\t"._g("Architecture to download: %s\n"), $arch);
-	} else {
-	    my $host = `dpkg --print-architecture`;
-	    chomp($host);
-		$msg .= sprintf(_g("Cannot determine architecture from '%s'. Using %s.\n"), $file, $host);
-	}
-	if (scalar (@foreignarches) > 0) {
-		$plural = ngettext("Foreign architecture", "Foreign architectures", scalar @foreignarches);
-		printf ("MultiArch:\t\t%s: %s\n", $plural, join(" ", sort @foreignarches));
-	}
-	if (defined $dir and $dir ne "") {
-		printf ("dir:\t\t\t"._g("Output directory: '%s'\n"), $dir);
-	} else {
-		$msg .= sprintf(_g("Cannot determine directory from '%s'.\n"), $file);
-	}
-	if ($unpack eq "true") {
-		printf ("unpack:\t\t\t"._g("extract all downloaded archives: %s\n"), $unpack);
-	} else {
-		printf ("unpack:\t\t\t"._g("extract all downloaded archives: %s\n"), "false");
-	}
-	print "configscript:\t\t$configsh\n" if (defined $configsh);
-	printf ("setupscript:\t\t%s: %s",_g("Script to be run after unpacking"),"$setupsh\n") if (defined $setupsh);
-	if (defined $omitrequired) {
-		printf ("omitrequired:\t\t%s\n",_g("'Priority required' packages are not included."));
-	} else {
-		printf ("omitrequired:\t\t%s\n",_g("'Priority: required' packages are included."));
-	}
-	if (defined $addimportant) {
-		printf("addimportant:\t\t"._g("'Priority: important' packages are included.\n"));
-	} else {
-		printf("addimportant:\t\t"._g("'Priority: important' packages are ignored.\n"));
-	}
-	if (defined $tidy) {
-		printf ("cleanup:\t\t"._g("remove apt cache data: true\n"));
-	} else {
-		printf ("cleanup:\t\t"._g("remove apt cache data: false\n"));
-	}
-	if (defined $noauth) {
-		printf ("noauth:\t\t\t"._g("allow the use of unauthenticated repositories: true\n"));
-	} else {
-		printf ("noauth:\t\t\t"._g("allow the use of unauthenticated repositories: false\n"));
-	}
-	if (defined $sourcedir) {
-		printf ("retainsources:\t"._g("Sources will be retained in: %s\n"), $sourcedir);
-	}
-	if (defined $tgzname) {
-		printf ("tarballname:\t\t"._g("Tarball name: '%s'\n"), $tgzname);
-	}
-	if (not defined $foreign or not defined $ignorenative) {
-		if (defined $omitpreinst) {
-			printf ("omitpreinst:\t\t"._g("Preinst scripts are not executed.\n"));
-		} else {
-			printf ("omitpreinst:\t\t"._g("Preinst scripts are executed with the install argument.\n"));
-		}
-		printf ("ignorenativearch:\t"._g("Packages will be configured.\n"));
-	} else {
-		printf ("omitpreinst:\t\t"._g("Preinst scripts are not executed.\n"));
-		printf ("ignorenativearch:\t"._g("Packages will not be configured.\n"));
-	}
-	if (defined $preffile) {
-		printf ("aptpreferences:\t\t"._g("Apt preferences file to use: '%s'\n"), $preffile);
-	} else {
-		printf ("aptpreferences:\t\t"._g("No apt preferences file. Default release: *\n"));
-	}
-	print "\n";
-	if (defined $msg) {
-		warn ("\n$msg\n");
-		exit 1;
-	}
-}
+__END__
+
+=head1 NAME
+
+multistrap - multiple repository bootstraps
+
+=head1 SYNOPSIS
+
+ multistrap [-a ARCH] [-d DIR] -f CONFIG_FILE
+ multistrap [--simulate] -f CONFIG_FILE
+ multistrap -?|-h|--help|--version
+
+=head1 OPTIONS
+
+=head2 General Options
+
+=over 8
+
+=item B<-?|-h|--help|--version>
+
+output the help text and exit successfully.
+
+=item B<--dry-run> B<--simulate>
+
+collate all the configuration settings and output a bare summary.
+
+=back
+
+=head2 Configuration Options
+
+These options overwrite values from the given configuration file which is
+documented in L<multistrap.conf(5)>.
+
+=over 8
+
+=item B<-a|--arch>
+
+architecture of the packages to put into the multistrap.
+
+=item B<-d|--dir>
+
+directory into which the bootstrap will be installed.
+
+=item B<-f|--file>
+
+configuration file for multistrap [required]
+
+=item B<-s|--shortcut>
+
+shortened version of -f for files in known locations without the .conf suffix.
+Searched locations are F</usr/share/multistrap/>, F</etc/multistrap.d/> and
+F<~/.config/multistrap>.
+
+=item B<--tidy-up>
+
+remove apt cache data, downloaded Packages files and the apt package cache.
+Same as cleanup=true.
+
+=item B<--no-auth>
+
+allow the use of unauthenticated repositories. Same as noauth=true
+
+=item B<--source-dir> DIR
+
+move the contents of var/cache/apt/archives/ from inside the chroot to the
+specified external directory, then add the Debian source packages for each
+used binary. Same as retainsources=DIR If the specified directory does not
+exist, nothing is done. Requires --tidy-up in order to calculate the full list
+of source packages, including dependencies.
+
+=back
+
+=head1 DESCRIPTION
+
+blubber
+
+=cut
diff --git a/t/config.t b/t/config.t
new file mode 100755
index 0000000..8cd334a
--- /dev/null
+++ b/t/config.t
@@ -0,0 +1,103 @@
+#!/usr/bin/perl
+
+# Copyright (C) 2015-2017  Johannes Schauer <josch@mister-muffin.de>
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to
+# deal in the Software without restriction, including without limitation the
+# rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+# sell copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+
+use strict;
+use warnings;
+
+use Test::More tests => 6;
+
+require "./multistrap";
+
+my %tests = (
+    complex => {
+	general => {
+	    include => [
+		[ 'branch1.ini', 'branch2.ini' ],
+		[
+		    [ ['shared.ini'], [], ['t/data/branch1.ini'] ],
+		    [
+			['intermediate.ini'],
+			[ [ ['shared.ini'], [], ['t/data/intermediate.ini'] ] ],
+			['t/data/branch2.ini']
+		    ]
+		],
+		['t/data/complex.ini']
+	    ],
+	    property => [
+		['1'],
+		[
+		    [
+			['2'], [ [ ['4'], [], ['t/data/shared.ini'] ] ],
+			['t/data/branch1.ini']
+		    ],
+		    [
+			['3'], [ [ ['4'], [], ['t/data/shared.ini'] ] ],
+			['t/data/branch2.ini']
+		    ],
+		],
+		['t/data/complex.ini']
+	    ],
+	    foo => [ ['bar'], [], ['t/data/intermediate.ini'] ]
+	}
+    },
+    shared => {
+	general => { property => [ ['4'], [], ['t/data/shared.ini'] ] }
+    },
+    intermediate => {
+	general => {
+	    include  => [ ['shared.ini'], [], ['t/data/intermediate.ini'] ],
+	    property => [ ['4'],          [], ['t/data/shared.ini'] ],
+	    foo      => [ ['bar'],        [], ['t/data/intermediate.ini'] ]
+	}
+    },
+    branch1 => {
+	general => {
+	    include => [ ['shared.ini'], [], ['t/data/branch1.ini'] ],
+	    property => [
+		['2'], [ [ ['4'], [], ['t/data/shared.ini'] ] ],
+		['t/data/branch1.ini']
+	    ]
+	}
+    },
+    branch2 => {
+	general => {
+	    include => [
+		['intermediate.ini'],
+		[ [ ['shared.ini'], [], ['t/data/intermediate.ini'] ] ],
+		['t/data/branch2.ini']
+	    ],
+	    property => [
+		['3'], [ [ ['4'], [], ['t/data/shared.ini'] ] ],
+		['t/data/branch2.ini']
+	    ],
+	    foo => [ ['bar'], [], ['t/data/intermediate.ini'] ]
+	}
+    },
+    concat => {
+	general => {
+	    property => [
+		[ '4', '1' ], [], [ 't/data/shared.ini', 't/data/simple.ini' ]
+	    ],
+	    include =>
+	    [ [ 'shared.ini', 'simple.ini' ], [], ['t/data/concat.ini'] ]
+	}
+    }
+);
+
+use Data::Dumper;
+print(Data::Dumper->Dump([multistrap::cascade("t/data/concat.ini")]));
+
+foreach my $k ( sort keys %tests ) {
+    is_deeply( multistrap::cascade("t/data/$k.ini"), $tests{$k}, "$k.ini" );
+}
diff --git a/t/critic.t b/t/critic.t
new file mode 100755
index 0000000..3219f34
--- /dev/null
+++ b/t/critic.t
@@ -0,0 +1,21 @@
+#!/usr/bin/perl
+
+# Copyright (C) 2015-2017  Johannes Schauer <josch@mister-muffin.de>
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to
+# deal in the Software without restriction, including without limitation the
+# rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+# sell copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+
+use strict;
+use warnings;
+
+use Test::Perl::Critic (-severity => 1);
+use Test::More tests => 1;
+
+critic_ok("./multistrap");
diff --git a/t/data/branch1.ini b/t/data/branch1.ini
new file mode 100644
index 0000000..266fc7b
--- /dev/null
+++ b/t/data/branch1.ini
@@ -0,0 +1,3 @@
+[general]
+include=shared.ini
+property=2
diff --git a/t/data/branch2.ini b/t/data/branch2.ini
new file mode 100644
index 0000000..8f090aa
--- /dev/null
+++ b/t/data/branch2.ini
@@ -0,0 +1,3 @@
+[general]
+include=intermediate.ini
+property=3
diff --git a/t/data/complex.ini b/t/data/complex.ini
new file mode 100644
index 0000000..c29ac27
--- /dev/null
+++ b/t/data/complex.ini
@@ -0,0 +1,4 @@
+[general]
+include=branch1.ini
+include=branch2.ini
+property=1
diff --git a/t/data/concat.ini b/t/data/concat.ini
new file mode 100644
index 0000000..2463a6a
--- /dev/null
+++ b/t/data/concat.ini
@@ -0,0 +1,3 @@
+[general]
+include=shared.ini
+include=simple.ini
diff --git a/t/data/intermediate.ini b/t/data/intermediate.ini
new file mode 100644
index 0000000..edbaaf9
--- /dev/null
+++ b/t/data/intermediate.ini
@@ -0,0 +1,3 @@
+[general]
+include=shared.ini
+foo=bar
diff --git a/t/data/shared.ini b/t/data/shared.ini
new file mode 100644
index 0000000..4bf71a0
--- /dev/null
+++ b/t/data/shared.ini
@@ -0,0 +1,2 @@
+[general]
+property=4
diff --git a/t/data/simple.ini b/t/data/simple.ini
new file mode 100644
index 0000000..14342ec
--- /dev/null
+++ b/t/data/simple.ini
@@ -0,0 +1,2 @@
+[general]
+property=1
diff --git a/t/perltidy.t b/t/perltidy.t
new file mode 100644
index 0000000..dc21d82
--- /dev/null
+++ b/t/perltidy.t
@@ -0,0 +1,5 @@
+#!/usr/bin/perl
+
+use Test::PerlTidy;
+
+run_tests(perltidyrc => 't/perltidyrc');