--- /dev/null
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Test::More tests => 16;
+use Test::Exception;
+
+BEGIN {
+ use_ok('Moose');
+}
+
+{
+ package BankAccount;
+ use Moose;
+
+ has '$.balance' => (accessor => 'balance', default => 0);
+
+ sub deposit {
+ my ($self, $amount) = @_;
+ $self->balance($self->balance + $amount);
+ }
+
+ sub withdraw {
+ my ($self, $amount) = @_;
+ my $current_balance = $self->balance();
+ ($current_balance >= $amount)
+ || confess "Account overdrawn";
+ $self->balance($current_balance - $amount);
+ }
+
+ package CheckingAccount;
+ use Moose;
+
+ use base 'BankAccount';
+
+ has '$.overdraft_account' => (accessor => 'overdraft_account');
+
+ before 'withdraw' => sub {
+ my ($self, $amount) = @_;
+ my $overdraft_amount = $amount - $self->balance();
+ if ($overdraft_amount > 0) {
+ $self->overdraft_account->withdraw($overdraft_amount);
+ $self->deposit($overdraft_amount);
+ }
+ };
+}
+
+
+my $savings_account = BankAccount->new(balance => 250);
+isa_ok($savings_account, 'BankAccount');
+
+is($savings_account->balance, 250, '... got the right savings balance');
+lives_ok {
+ $savings_account->withdraw(50);
+} '... withdrew from savings successfully';
+is($savings_account->balance, 200, '... got the right savings balance after withdrawl');
+
+$savings_account->deposit(150);
+is($savings_account->balance, 350, '... got the right savings balance after deposit');
+
+my $checking_account = CheckingAccount->new(
+ balance => 100,
+ overdraft_account => $savings_account
+ );
+isa_ok($checking_account, 'CheckingAccount');
+isa_ok($checking_account, 'BankAccount');
+
+is($checking_account->overdraft_account, $savings_account, '... got the right overdraft account');
+
+is($checking_account->balance, 100, '... got the right checkings balance');
+
+lives_ok {
+ $checking_account->withdraw(50);
+} '... withdrew from checking successfully';
+is($checking_account->balance, 50, '... got the right checkings balance after withdrawl');
+is($savings_account->balance, 350, '... got the right savings balance after checking withdrawl (no overdraft)');
+
+lives_ok {
+ $checking_account->withdraw(200);
+} '... withdrew from checking successfully';
+is($checking_account->balance, 0, '... got the right checkings balance after withdrawl');
+is($savings_account->balance, 200, '... got the right savings balance after overdraft withdrawl');
+