Add unit tests for BankAccount class

Author: seer-by-sentry[bot]

billing/tests/test_accounts.py

@@ -0,0 +1,59 @@
+import unittest
+from billing.accounts import BankAccount
+
+class TestBankAccount(unittest.TestCase):
+    def setUp(self):
+        self.account = BankAccount("John Doe", 1000.0)
+
+    def test_initialization(self):
+        self.assertEqual(self.account.owner, "John Doe")
+        self.assertEqual(self.account.balance, 1000.0)
+
+    def test_initialization_with_negative_balance(self):
+        with self.assertRaises(ValueError):
+            BankAccount("Jane Doe", -100.0)
+
+    def test_deposit(self):
+        new_balance = self.account.deposit(500.0)
+        self.assertEqual(new_balance, 1500.0)
+        self.assertEqual(self.account.balance, 1500.0)
+
+    def test_deposit_negative_amount(self):
+        with self.assertRaises(ValueError):
+            self.account.deposit(-100.0)
+
+    def test_withdraw(self):
+        new_balance = self.account.withdraw(300.0)
+        self.assertEqual(new_balance, 700.0)
+        self.assertEqual(self.account.balance, 700.0)
+
+    def test_withdraw_negative_amount(self):
+        with self.assertRaises(ValueError):
+            self.account.withdraw(-100.0)
+
+    def test_withdraw_insufficient_funds(self):
+        with self.assertRaises(ValueError):
+            self.account.withdraw(1500.0)
+
+    def test_transfer(self):
+        other_account = BankAccount("Jane Doe", 500.0)
+        sender_balance, recipient_balance = self.account.transfer(other_account, 300.0)
+        self.assertEqual(sender_balance, 700.0)
+        self.assertEqual(recipient_balance, 800.0)
+        self.assertEqual(self.account.balance, 700.0)
+        self.assertEqual(other_account.balance, 800.0)
+
+    def test_transfer_invalid_recipient(self):
+        with self.assertRaises(ValueError):
+            self.account.transfer("not a bank account", 100.0)
+
+    def test_transfer_insufficient_funds(self):
+        other_account = BankAccount("Jane Doe", 500.0)
+        with self.assertRaises(ValueError):
+            self.account.transfer(other_account, 1500.0)
+
+    def test_get_balance(self):
+        self.assertEqual(self.account.get_balance(), 1000.0)
+
+if __name__ == '__main__':
+    unittest.main()