--- /dev/null
+<?php
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+class BankAccountException extends RuntimeException
+{
+}
+
+/**
+ * A bank account.
+ *
+ * @since Class available since Release 2.3.0
+ */
+class BankAccount
+{
+ /**
+ * The bank account's balance.
+ *
+ * @var float
+ */
+ protected $balance = 0;
+
+ /**
+ * Returns the bank account's balance.
+ *
+ * @return float
+ */
+ public function getBalance()
+ {
+ return $this->balance;
+ }
+
+ /**
+ * Sets the bank account's balance.
+ *
+ * @param float $balance
+ *
+ * @throws BankAccountException
+ */
+ protected function setBalance($balance)
+ {
+ if ($balance >= 0) {
+ $this->balance = $balance;
+ } else {
+ throw new BankAccountException;
+ }
+ }
+
+ /**
+ * Deposits an amount of money to the bank account.
+ *
+ * @param float $balance
+ *
+ * @throws BankAccountException
+ */
+ public function depositMoney($balance)
+ {
+ $this->setBalance($this->getBalance() + $balance);
+
+ return $this->getBalance();
+ }
+
+ /**
+ * Withdraws an amount of money from the bank account.
+ *
+ * @param float $balance
+ *
+ * @throws BankAccountException
+ */
+ public function withdrawMoney($balance)
+ {
+ $this->setBalance($this->getBalance() - $balance);
+
+ return $this->getBalance();
+ }
+}