@covers BankAccount::getBalance @covers BankAccount::depositMoney @covers BankAccount::withdrawMoney
public function testDepositWithdrawMoney() {
  $this
    ->assertEquals(0, $this->ba
    ->getBalance());
  $this->ba
    ->depositMoney(1);
  $this
    ->assertEquals(1, $this->ba
    ->getBalance());
  $this->ba
    ->withdrawMoney(1);
  $this
    ->assertEquals(0, $this->ba
    ->getBalance());
}