baseline: 批次A-D 成果 + membership 半成品（测试红）

backend/tests/test_p0_credit.py

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+"""P0 #5 信用额度落地集成测试。
+
+覆盖：限额内通过、超限拒绝、force 放行+预警通知、接近 90% 预警、无限额不校验。
+"""
+
+import pytest
+from datetime import date
+from decimal import Decimal
+from model_bakery import baker
+
+from apps.catalog.models import Product
+from apps.inventory.models import Warehouse
+from apps.partner.models import Customer
+from apps.finance.models import Receivable
+from apps.notify.models import Notification
+from apps.sales import services as sales_services
+from apps.sales.services import CreditLimitExceeded
+
+
+@pytest.fixture
+def warehouse(db, tenant):
+    return baker.make(Warehouse, tenant=tenant, code="WH01", name="主仓")
+
+
+@pytest.fixture
+def product(db, tenant):
+    return baker.make(Product, tenant=tenant, code="P001", name="商品A",
+                      sale_price=Decimal("100"))
+
+
+@pytest.fixture
+def customer(db, tenant):
+    return baker.make(Customer, tenant=tenant, code="C001", name="受限客户",
+                      credit_limit=Decimal("1000"))
+
+
+def _stock_in(tenant, warehouse, product, qty):
+    from apps.inventory import services as inv_services
+    inv_services.inbound(
+        tenant=tenant, warehouse=warehouse, product=product,
+        quantity=Decimal(str(qty)), unit_cost=Decimal("50"),
+    )
+
+
+def _make_receivable(tenant, customer, amount, paid=0):
+    return baker.make(
+        Receivable, tenant=tenant, customer=customer, bill_no="RC-OLD",
+        bill_date=date.today(), total_amount=Decimal(str(amount)),
+        paid_amount=Decimal(str(paid)), status="partial" if paid else "open",
+    )
+
+
+def test_confirm_within_limit_passes(tenant, warehouse, customer, product):
+    _make_receivable(tenant, customer, 400)
+    _stock_in(tenant, warehouse, product, 10)
+    bill = sales_services.create_sales_bill(
+        tenant=tenant, customer=customer, warehouse=warehouse,
+        lines=[{"product": product, "quantity": 5, "unit_price": 100}],  # 500
+    )
+    sales_services.confirm_sales_bill(bill)
+    assert bill.state == "confirmed"
+
+
+def test_confirm_over_limit_rejects_and_rolls_back(tenant, warehouse, customer, product):
+    _make_receivable(tenant, customer, 700)
+    _stock_in(tenant, warehouse, product, 10)
+    bill = sales_services.create_sales_bill(
+        tenant=tenant, customer=customer, warehouse=warehouse,
+        lines=[{"product": product, "quantity": 5, "unit_price": 100}],  # 500 → 1200 > 1000
+    )
+    from apps.inventory.models import Stock
+    with pytest.raises(CreditLimitExceeded):
+        sales_services.confirm_sales_bill(bill)
+    # 事务回滚：库存未扣、应收未生成、状态未变
+    assert bill.state == "draft"
+    assert Stock.objects.get(product=product).on_hand == Decimal("10")
+    assert not Receivable.objects.filter(source_ref=bill.bill_no).exists()
+
+
+def test_confirm_over_limit_force_passes_with_alert(tenant, warehouse, customer, product):
+    _make_receivable(tenant, customer, 700)
+    _stock_in(tenant, warehouse, product, 10)
+    bill = sales_services.create_sales_bill(
+        tenant=tenant, customer=customer, warehouse=warehouse,
+        lines=[{"product": product, "quantity": 5, "unit_price": 100}],
+    )
+    sales_services.confirm_sales_bill(bill, force=True)
+    assert bill.state == "confirmed"
+    assert Notification.objects.filter(
+        tenant=tenant, extra_data__forced=True
+    ).count() == 1
+
+
+def test_confirm_near_limit_warns(tenant, warehouse, customer, product):
+    """占用达 90% 发预警但不阻断：400 旧账 + 500 新单 = 900 = 90%。"""
+    _make_receivable(tenant, customer, 400)
+    _stock_in(tenant, warehouse, product, 10)
+    bill = sales_services.create_sales_bill(
+        tenant=tenant, customer=customer, warehouse=warehouse,
+        lines=[{"product": product, "quantity": 5, "unit_price": 100}],
+    )
+    sales_services.confirm_sales_bill(bill)
+    assert bill.state == "confirmed"
+    assert Notification.objects.filter(
+        tenant=tenant, title__contains="信用额度即将用尽"
+    ).count() == 1
+
+
+def test_no_limit_no_check(tenant, warehouse, product):
+    """credit_limit=0 表示不启用管控。"""
+    c = baker.make(Customer, tenant=tenant, code="C002", name="不限客户",
+                   credit_limit=Decimal("0"))
+    _stock_in(tenant, warehouse, product, 10)
+    bill = sales_services.create_sales_bill(
+        tenant=tenant, customer=c, warehouse=warehouse,
+        lines=[{"product": product, "quantity": 10, "unit_price": 100}],  # 1000 无额度
+    )
+    sales_services.confirm_sales_bill(bill)
+    assert bill.state == "confirmed"
+
+
+def test_rounded_bill_counts_net_amount(tenant, warehouse, customer, product):
+    """抹零后按净额计入占用：旧账 44 + 行合计 1000.56 抹零后 1000 = 1044 ≤ 1000？不，
+    这里验证"净额而非毛额"计入：旧账 600 + 1000.56→1000 = 1600 > 1000 必须拒绝；
+    若按毛额计入 600+1000.56 更超。改用不超限场景：旧账 0 + 999 抹零… 直接验证
+    旧账 44 + 1000.56 抹成 1000 = 1044 超限 → 用 force 之外，改为验证边界：
+    旧账 0.56，本单 1000.56 抹到 1000，合计 1000.56 → 超 1000 拒绝；
+    再把旧账清 0.44（收 0.12）后合计 1000.00 恰好通过。
+    """
+    from decimal import Decimal as D
+    recv = _make_receivable(tenant, customer, 1)
+    _stock_in(tenant, warehouse, product, 10)
+    bill = sales_services.create_sales_bill(
+        tenant=tenant, customer=customer, warehouse=warehouse,
+        lines=[{"product": product, "quantity": 10, "unit_price": 100.05}],
+        round_to="1",
+    )
+    # 10×100.05 = 1000.5 → 抹到 1000
+    assert bill.total_amount == D("1000")
+    assert bill.round_off == D("0.5")
+    # outstanding = 1 + 1000 = 1001 > 1000 → 拒绝
+    with pytest.raises(CreditLimitExceeded):
+        sales_services.confirm_sales_bill(bill)
+    # 客户还掉 1 元旧账 → outstanding 1000 = 限额，恰好通过
+    recv.paid_amount = D("1")
+    recv.status = "paid"
+    recv.save()
+    sales_services.confirm_sales_bill(bill)
+    assert bill.state == "confirmed"