""" inventory/tests/test_services.py Tests for inventory service layer (stock movements, sales, payouts). """ from datetime import date from decimal import Decimal from django.contrib.auth import get_user_model from django.test import TestCase from catalog_app.models import Author, Book from inventory.models import ( AuthorPayout, InventoryBalance, InventoryTransaction, Sale, SaleItem, StockLocation, ) from inventory.services.inventory_service import ( adjust_stock, receive_stock, transfer_stock, ) from inventory.services.payout_service import ( approve_payout, generate_payout, mark_payout_paid, ) from inventory.services.sales_service import calculate_item_margins, record_sale User = get_user_model() # --------------------------------------------------------------------------- # Fixtures # --------------------------------------------------------------------------- def make_author(**kw): return Author.objects.create( name=kw.pop("name", "Test Author"), default_my_keep_percent=kw.pop("my_keep_percent", Decimal("25.00")), default_author_pay_percent=kw.pop("author_pay_percent", Decimal("75.00")), **kw, ) def make_book(author, **kw): return Book.objects.create( title=kw.pop("title", "Test Book"), author=author, price=kw.pop("price", Decimal("1500.00")), my_keep_percent=kw.pop("my_keep_percent", Decimal("25.00")), reorder_level=kw.pop("reorder_level", 5), track_inventory=True, is_listed=True, **kw, ) def make_location(code="WH001", **kw): return StockLocation.objects.create( name=kw.pop("name", "Warehouse"), code=code, location_type=kw.pop("location_type", StockLocation.TYPE_WAREHOUSE), **kw, ) def make_user(username="staff"): return User.objects.create_user(username=username, password="pass", is_staff=True) # --------------------------------------------------------------------------- # Stock movement tests # --------------------------------------------------------------------------- class ReceiveStockTest(TestCase): def setUp(self): self.author = make_author() self.book = make_book(self.author) self.location = make_location() self.user = make_user() def test_receive_creates_balance(self): receive_stock(book=self.book, location=self.location, quantity=10, user=self.user) balance = InventoryBalance.objects.get(book=self.book, location=self.location) self.assertEqual(balance.quantity_on_hand, 10) def test_receive_creates_transaction(self): receive_stock(book=self.book, location=self.location, quantity=10, user=self.user) tx = InventoryTransaction.objects.get(book=self.book, destination_location=self.location) self.assertEqual(tx.transaction_type, InventoryTransaction.TYPE_RECEIPT) self.assertEqual(tx.quantity, 10) def test_receive_accumulates(self): receive_stock(book=self.book, location=self.location, quantity=10, user=self.user) receive_stock(book=self.book, location=self.location, quantity=5, user=self.user) balance = InventoryBalance.objects.get(book=self.book, location=self.location) self.assertEqual(balance.quantity_on_hand, 15) def test_receive_rejects_zero(self): with self.assertRaises(ValueError): receive_stock(book=self.book, location=self.location, quantity=0, user=self.user) class TransferStockTest(TestCase): def setUp(self): self.author = make_author() self.book = make_book(self.author) self.src = make_location(code="SRC") self.dst = make_location(code="DST") self.user = make_user() receive_stock(book=self.book, location=self.src, quantity=20, user=self.user) def test_transfer_moves_stock(self): transfer_stock(book=self.book, source=self.src, destination=self.dst, quantity=8, user=self.user) src_bal = InventoryBalance.objects.get(book=self.book, location=self.src) dst_bal = InventoryBalance.objects.get(book=self.book, location=self.dst) self.assertEqual(src_bal.quantity_on_hand, 12) self.assertEqual(dst_bal.quantity_on_hand, 8) def test_transfer_insufficient_stock_raises(self): with self.assertRaises(ValueError): transfer_stock(book=self.book, source=self.src, destination=self.dst, quantity=100, user=self.user) def test_transfer_same_location_raises(self): with self.assertRaises(ValueError): transfer_stock(book=self.book, source=self.src, destination=self.src, quantity=5, user=self.user) class AdjustStockTest(TestCase): def setUp(self): self.author = make_author() self.book = make_book(self.author) self.location = make_location() self.user = make_user() receive_stock(book=self.book, location=self.location, quantity=10, user=self.user) def test_adjust_up(self): adjust_stock(book=self.book, location=self.location, new_quantity=15, user=self.user) balance = InventoryBalance.objects.get(book=self.book, location=self.location) self.assertEqual(balance.quantity_on_hand, 15) def test_adjust_down(self): adjust_stock(book=self.book, location=self.location, new_quantity=3, user=self.user) balance = InventoryBalance.objects.get(book=self.book, location=self.location) self.assertEqual(balance.quantity_on_hand, 3) def test_adjust_no_change_is_noop(self): initial_tx_count = InventoryTransaction.objects.count() adjust_stock(book=self.book, location=self.location, new_quantity=10, user=self.user) self.assertEqual(InventoryTransaction.objects.count(), initial_tx_count) # --------------------------------------------------------------------------- # Margin calculation tests (critical business logic) # --------------------------------------------------------------------------- class MarginCalculationTest(TestCase): def setUp(self): self.author = make_author() self.book = make_book(self.author, my_keep_percent=Decimal("25.00")) def test_no_discount(self): result = calculate_item_margins( book=self.book, quantity=1, unit_price=Decimal("1000.00"), discount_percent=Decimal("0"), ) self.assertEqual(result["gross_amount"], Decimal("1000.00")) self.assertEqual(result["net_amount"], Decimal("1000.00")) self.assertEqual(result["my_profit_amount"], Decimal("250.00")) self.assertEqual(result["author_payout_amount"], Decimal("750.00")) def test_discount_applied_before_split(self): # 10% discount on 1000 → net 900 # 25% of 900 = 225 platform; 75% of 900 = 675 author result = calculate_item_margins( book=self.book, quantity=1, unit_price=Decimal("1000.00"), discount_percent=Decimal("10"), ) self.assertEqual(result["net_amount"], Decimal("900.00")) self.assertEqual(result["my_profit_amount"], Decimal("225.00")) self.assertEqual(result["author_payout_amount"], Decimal("675.00")) def test_quantity_multiplied(self): result = calculate_item_margins( book=self.book, quantity=3, unit_price=Decimal("1000.00"), discount_percent=Decimal("0"), ) self.assertEqual(result["gross_amount"], Decimal("3000.00")) self.assertEqual(result["my_profit_amount"], Decimal("750.00")) def test_margins_sum_to_net(self): result = calculate_item_margins( book=self.book, quantity=2, unit_price=Decimal("750.00"), discount_percent=Decimal("15"), ) self.assertAlmostEqual( float(result["my_profit_amount"] + result["author_payout_amount"]), float(result["net_amount"]), places=2, ) # --------------------------------------------------------------------------- # Record sale tests # --------------------------------------------------------------------------- class RecordSaleTest(TestCase): def setUp(self): self.author = make_author() self.book = make_book(self.author) self.location = make_location() self.user = make_user() receive_stock(book=self.book, location=self.location, quantity=50, user=self.user) def test_record_sale_creates_sale_and_items(self): sale = record_sale( sale_channel=Sale.CHANNEL_DIRECT, sale_date=date.today(), items=[{ "book": self.book, "quantity": 3, "unit_price": Decimal("1500.00"), "discount_percent": Decimal("0"), "stock_location": self.location, }], user=self.user, ) self.assertIsNotNone(sale.pk) self.assertEqual(sale.items.count(), 1) def test_record_sale_deducts_stock(self): record_sale( sale_channel=Sale.CHANNEL_DIRECT, sale_date=date.today(), items=[{ "book": self.book, "quantity": 5, "unit_price": Decimal("1500.00"), "discount_percent": Decimal("0"), "stock_location": self.location, }], user=self.user, ) balance = InventoryBalance.objects.get(book=self.book, location=self.location) self.assertEqual(balance.quantity_on_hand, 45) def test_record_sale_insufficient_stock_raises(self): with self.assertRaises(ValueError): record_sale( sale_channel=Sale.CHANNEL_DIRECT, sale_date=date.today(), items=[{ "book": self.book, "quantity": 999, "unit_price": Decimal("1500.00"), "discount_percent": Decimal("0"), "stock_location": self.location, }], user=self.user, ) def test_sale_totals_calculated_correctly(self): sale = record_sale( sale_channel=Sale.CHANNEL_DIRECT, sale_date=date.today(), items=[{ "book": self.book, "quantity": 2, "unit_price": Decimal("1000.00"), "discount_percent": Decimal("10"), "stock_location": self.location, }], user=self.user, ) # 2 × 1000 = 2000 gross; 10% discount = 200; net = 1800 self.assertEqual(sale.total_gross, Decimal("2000.00")) self.assertEqual(sale.total_discount, Decimal("200.00")) self.assertEqual(sale.total_net, Decimal("1800.00")) # --------------------------------------------------------------------------- # Payout service tests # --------------------------------------------------------------------------- class PayoutServiceTest(TestCase): def setUp(self): self.author = make_author() self.book = make_book(self.author) self.location = make_location() self.user = make_user() receive_stock(book=self.book, location=self.location, quantity=50, user=self.user) self.sale = record_sale( sale_channel=Sale.CHANNEL_DIRECT, sale_date=date(2025, 1, 15), items=[{ "book": self.book, "quantity": 2, "unit_price": Decimal("1000.00"), "discount_percent": Decimal("0"), "stock_location": self.location, }], user=self.user, ) def test_generate_payout(self): payout = generate_payout( author=self.author, period_type=AuthorPayout.PERIOD_MONTHLY, period_start=date(2025, 1, 1), period_end=date(2025, 1, 31), user=self.user, ) self.assertEqual(payout.status, AuthorPayout.STATUS_PENDING) self.assertGreater(payout.total_earnings, Decimal("0")) def test_approve_payout_marks_items(self): payout = generate_payout( author=self.author, period_type=AuthorPayout.PERIOD_MONTHLY, period_start=date(2025, 1, 1), period_end=date(2025, 1, 31), user=self.user, ) approver = make_user("approver") approve_payout(payout=payout, approver=approver) payout.refresh_from_db() self.assertEqual(payout.status, AuthorPayout.STATUS_APPROVED) # SaleItems should be locked self.assertTrue( self.sale.items.filter(payout_included=True).exists() ) def test_double_generate_excludes_paid_items(self): payout1 = generate_payout( author=self.author, period_type=AuthorPayout.PERIOD_MONTHLY, period_start=date(2025, 1, 1), period_end=date(2025, 1, 31), user=self.user, ) approve_payout(payout=payout1, approver=self.user) # Second generate should return empty (no new items) payout2 = generate_payout( author=self.author, period_type=AuthorPayout.PERIOD_MONTHLY, period_start=date(2025, 1, 1), period_end=date(2025, 1, 31), user=self.user, ) self.assertEqual(payout2.total_earnings, Decimal("0")) def test_mark_payout_paid(self): payout = generate_payout( author=self.author, period_type=AuthorPayout.PERIOD_MONTHLY, period_start=date(2025, 1, 1), period_end=date(2025, 1, 31), user=self.user, ) approve_payout(payout=payout, approver=self.user) mark_payout_paid( payout=payout, payment_method="M-Pesa", payment_reference="QWE12345", payment_date=date(2025, 2, 1), user=self.user, ) payout.refresh_from_db() self.assertEqual(payout.status, AuthorPayout.STATUS_PAID) self.assertEqual(payout.payment_reference, "QWE12345")