first cut of a product with a version number

hjwp · hjwp · commit 48cb8b984bc7 · 2024-03-01T15:01:35.000Z
diff --git a/src/allocation/domain/model.py b/src/allocation/domain/model.py
@@ -9,14 +9,16 @@ class OutOfStock(Exception):
 
 
 class Product:
-    def __init__(self, sku: str, batches: List[Batch]):
+    def __init__(self, sku: str, batches: List[Batch], version_number: int = 0):
         self.sku = sku
         self.batches = batches
+        self.version_number = version_number
 
     def allocate(self, line: OrderLine) -> str:
         try:
             batch = next(b for b in sorted(self.batches) if b.can_allocate(line))
             batch.allocate(line)
+            self.version_number += 1
             return batch.reference
         except StopIteration:
             raise OutOfStock(f"Out of stock for sku {line.sku}")
diff --git a/tests/unit/test_product.py b/tests/unit/test_product.py
@@ -49,3 +49,13 @@ def test_raises_out_of_stock_exception_if_cannot_allocate():
 
     with pytest.raises(OutOfStock, match="SMALL-FORK"):
         product.allocate(OrderLine("order2", "SMALL-FORK", 1))
+
+
+def test_increments_version_number():
+    line = OrderLine("oref", "SCANDI-PEN", 10)
+    product = Product(
+        sku="SCANDI-PEN", batches=[Batch("b1", "SCANDI-PEN", 100, eta=None)]
+    )
+    product.version_number = 7
+    product.allocate(line)
+    assert product.version_number == 8
