Test::GreaterVersion - Test if you incremented VERSION

  has_greater_version('My::Module');

  has_greater_version_than_cpan('My::Module');

  Module Path
    doc
    examples
    lib
    t

package Test::GreaterVersion;

use strict;
use warnings;

use ExtUtils::MakeMaker;
use CPAN;
use CPAN::Version;
use Cwd;
use File::Spec;
use Test::Builder;

use base qw(Exporter);
our @EXPORT = qw(has_greater_version
  has_greater_version_than_cpan);

our $VERSION = 0.010;

# the development version of the module is expected
# to be below this directory
our $libdir = 'lib';

our $Test = Test::Builder->new;

sub import {
	my ($self) = shift;
	my $pack = caller;

	$Test->exported_to($pack);
	$Test->plan(@_);

	$self->export_to_level( 1, $self, 'has_greater_version' );
	$self->export_to_level( 1, $self, 'has_greater_version_than_cpan' );
}

sub has_greater_version {
	my ($module) = @_;

	# fail if the module's name is missing
	unless ($module) {
		return $Test->diag("You didn't specify a module name");
	}

	my $version_from_lib = _get_version_from_lib($module);
	unless (defined $version_from_lib) {
		# fail if module is not in lib
		return $Test->diag('module is not in lib');
	}

	if ($version_from_lib eq 'undef') {
		# fail if module has no version
		return $Test->diag('module in lib has no version');
	}

	# so the module in lib has a version
	$Test->diag('module is in lib and has version');

	my $version_installed = _get_installed_version($module);
	unless (defined $version_installed) {
		$Test->diag('module is not installed');

		# module doesn't seem to be installed, that's okay --
		# it might be new
		return 1;
	}

 	if ($version_installed eq 'undef') {
		$Test->diag('version of installed module is not defined');

		# installed module seems to have no version, that's okay
		# if the module in lib has
		return 1;
 	}
 	
 	# so the installed module has a version, too
	$Test->diag('module is installed and has version');
 	# let's compare them
 	
	$Test->ok( CPAN::Version->vgt( $version_from_lib, $version_installed ),
		"$module has greater version" );
}

sub has_greater_version_than_cpan {
	my ($module) = @_;

	# fail if the module's name is missing
	unless ($module) {
		return $Test->diag('You didn\'t specify a module name');
	}

	my $version_from_lib = _get_version_from_lib($module);
	unless (defined $version_from_lib) {
		# fail if module is not in lib
		return $Test->diag('module is not in lib');
	}

	if ($version_from_lib eq 'undef') {
		# fail if module has no version
		return $Test->diag('module in lib has no version');
	}

	# so the module in lib has a version
	$Test->diag('module is in lib and has version');

	my $cpan_version = _get_version_from_cpan($module);
	unless ($cpan_version) {
		$Test->diag('module is not on CPAN or has no version');

		# module doesn't seem to be on CPAN, that's okay --
		# it might be new. If it has no version that's okay,
		# too -- we have one
		return 1;
	}
 	
 	# so the module on CPAN has a version, too
	$Test->diag('module is on CPAN and has version');
 	# let's compare them

	$Test->ok( CPAN::Version->vgt( $version_from_lib, $cpan_version ),
		"$module has greater version than on CPAN" );
}

sub _get_installed_version {
	my ($module) = @_;

	# Strip blib from @INC so the CPAN::Shell
	# won't find the module even if it's there.
	# (Tests add blib to @INC).
	# Localize @INC so we won't affect others
	local @INC = grep { $_ !~ /blib/ } @INC;

	my $file = _module_to_file($module);

	my $bestv;
	for my $incdir (@INC) {
		my $bfile = File::Spec->catfile( $incdir, $file );

		# skip if it's not a file
		next unless -f $bfile;

		# get the version
		my $foundv = MM->parse_version($bfile);

		# remember which version is greatest
		if ( !$bestv || CPAN::Version->vgt( $foundv, $bestv ) ) {
			$bestv = $foundv;
		}
	}

	return $bestv;
}

sub _get_version_from_lib {
	my $module = shift;

	my $cwd  = getcwd();
	my $file =
	  File::Spec->catfile( $cwd, $libdir, _module_to_file($module));    

	unless (-f $file) {
		$Test->diag("file '$file' doesn't exist");
		return;
	}
	
	# try to get the version
	my $code = sub { MM->parse_version($file) };
	my ( $version, $error ) = $Test->_try($code);

	# fail on errors
	return $Test->diag("parse_version had errors: $@")
	  if $error;

	return $version;

}

# convert module name to file under lib (OS-independent)
sub _module_to_file {
	my ($module) = @_;

	# get list of components
	my @components = split( /::/, $module );

	# a/b.pm under UNI* for 'a::b'
	my $file=File::Spec->catfile(@components);

	return "$file.pm";
}

sub _get_version_from_cpan {
	my ($module) = @_;

	# Turn off coloured output of the CPAN shell.
	# This breaks the test/Harness/whatever.
	CPAN::HandleConfig->load();
	$CPAN::Config->{colorize_output} = 0;

	# taken from CPAN manpage
	my $m = CPAN::Shell->expand( 'Module', $module );

	# the module is not on CPAN or something broke
	unless ($m) {
		$Test->diag("CPAN-version of '$module' not available");
		return;
	}

	# there is a version on CPAN
	return $m->cpan_version();
}

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