feat: big

cost/tests/test_models.py

@@ -142,4 +142,54 @@ class CostEntryModelTests(TestCase):
             occurred_at=date(2026, 6, 1),
         )
         self.assertFalse(bool(entry.image1))
-        self.assertFalse(bool(entry.image2))
+        self.assertFalse(bool(entry.image2))
+
+    def test_formula_amount_calculated_on_create(self):
+        entry = cost_models.CostEntry.objects.create(
+            merchant=self.merchant,
+            category=self.category,
+            amount=None,
+            unit_amount=Decimal('120.00'),
+            quantity=Decimal('2.5'),
+            unit_name='人天',
+            occurred_at=date(2026, 6, 1),
+        )
+        self.assertEqual(entry.amount, Decimal('300.00'))
+        self.assertEqual(entry.unit_name, '人天')
+
+    def test_formula_amount_recalculated_on_update(self):
+        entry = cost_models.CostEntry.objects.create(
+            merchant=self.merchant,
+            category=self.category,
+            amount=Decimal('300.00'),
+            unit_amount=Decimal('100.00'),
+            quantity=Decimal('3'),
+            occurred_at=date(2026, 6, 1),
+        )
+        entry.quantity = Decimal('4')
+        entry.amount = Decimal('999.00')
+        entry.save()
+        entry.refresh_from_db()
+        self.assertEqual(entry.amount, Decimal('400.00'))
+
+    def test_formula_partial_fields_raise_validation_error(self):
+        with self.assertRaises(ValidationError) as ctx:
+            cost_models.CostEntry.objects.create(
+                merchant=self.merchant,
+                category=self.category,
+                amount=None,
+                unit_amount=Decimal('100.00'),
+                quantity=None,
+                occurred_at=date(2026, 6, 1),
+            )
+        self.assertIn('quantity', ctx.exception.message_dict)
+
+    def test_manual_amount_required_without_formula(self):
+        with self.assertRaises(ValidationError) as ctx:
+            cost_models.CostEntry.objects.create(
+                merchant=self.merchant,
+                category=self.category,
+                amount=None,
+                occurred_at=date(2026, 6, 1),
+            )
+        self.assertIn('amount', ctx.exception.message_dict)

cost/tests/test_services.py

@@ -171,6 +171,33 @@ class CreateCostEntryTests(TestCase):
         self.assertEqual(entry.source_id, '')
         self.assertEqual(entry.remarks, '')
 
+    def test_create_cost_entry_with_formula_fields(self):
+        """传入 unit_amount + quantity 时自动计算最终 amount"""
+        entry = cost_services.create_cost_entry(
+            merchant=self.merchant,
+            category=self.category,
+            unit_amount=Decimal('180.00'),
+            quantity=Decimal('2'),
+            unit_name='人天',
+            occurred_at=date(2026, 6, 4),
+        )
+        self.assertEqual(entry.amount, Decimal('360.00'))
+        self.assertEqual(entry.unit_amount, Decimal('180.0000'))
+        self.assertEqual(entry.quantity, Decimal('2.0000'))
+        self.assertEqual(entry.unit_name, '人天')
+
+    def test_create_cost_entry_formula_overrides_amount(self):
+        """倍数型支出以公式结果作为最终统计金额"""
+        entry = cost_services.create_cost_entry(
+            merchant=self.merchant,
+            category=self.category,
+            amount=Decimal('999.00'),
+            unit_amount=Decimal('120.00'),
+            quantity=Decimal('3'),
+            occurred_at=date(2026, 6, 4),
+        )
+        self.assertEqual(entry.amount, Decimal('360.00'))
+
 
 class MockCostProvider:
     """测试用 Provider"""
@@ -222,6 +249,33 @@ class CollectFromProviderTests(TestCase):
         self.assertEqual(cost_models.CostEntry.objects.count(), 2)
         self.assertEqual(cost_models.CostCategory.objects.count(), 2)
 
+
+    def test_collect_creates_formula_entries(self):
+        """Provider 可以提供 unit_amount + quantity，由 cost 模块计算 amount"""
+        entries = [
+            CostEntryInput(
+                category_key='temp_worker', category_name='临时工工资',
+                amount=None, unit_amount=Decimal('200.00'), quantity=Decimal('3'),
+                unit_name='人天', occurred_at=date(2026, 6, 3),
+                source_module='test', source_id='T001',
+            ),
+        ]
+        provider = MockCostProvider(entries)
+
+        result = cost_services.collect_from_provider(
+            provider=provider,
+            merchant=self.merchant,
+            start_date=date(2026, 6, 1),
+            end_date=date(2026, 6, 30),
+        )
+
+        self.assertEqual(result['created_count'], 1)
+        entry = cost_models.CostEntry.objects.get()
+        self.assertEqual(entry.amount, Decimal('600.00'))
+        self.assertEqual(entry.unit_amount, Decimal('200.0000'))
+        self.assertEqual(entry.quantity, Decimal('3.0000'))
+        self.assertEqual(entry.unit_name, '人天')
+
     def test_collect_returns_not_list_raises(self):
         """Provider 返回非 list 抛 TypeError"""
         class BadProvider: