deallocate and fix issues

flask_app.py

@@ -30,3 +30,20 @@ def allocate_endpoint():
         return {"message": str(e)}, 400
 
     return {"batchref": batchref}, 201
+
+
+
+@app.route("/deallocate", methods=["POST"])
+def deallocate_endpoint():
+    session = get_session()
+    repo = repository.SqlAlchemyRepository(session)
+
+    order_id = request.json["orderid"]
+    sku = request.json["sku"]
+
+    try:
+        batchref = services.deallocate(order_id, sku,repo, session)
+    except Exception as e:
+        return {"message": str(e)}, 400
+
+    return {"batchref": batchref}, 201

repository.py

@@ -10,6 +10,10 @@ def add(self, batch: model.Batch):
     @abc.abstractmethod
     def get(self, reference) -> model.Batch:
         raise NotImplementedError
+
+    @abc.abstractmethod
+    def get_line_item(self, order_id: str, sku: str) -> model.OrderLine:
+        raise NotImplementedError
 
 
 class SqlAlchemyRepository(AbstractRepository):
@@ -24,3 +28,10 @@ def get(self, reference):
 
     def list(self):
         return self.session.query(model.Batch).all()
+
+    def get_line_item(self, order_id: str, sku: str) -> model.OrderLine:
+        return (
+            self.session.query(model.OrderLine)
+            .filter_by(orderid=order_id, sku=sku)
+            .one()
+        )

requirements.txt

@@ -1,5 +1,5 @@
 pytest
-sqlalchemy
+sqlalchemy==1.4.49
 flask
 psycopg2-binary
 requests

services.py

@@ -1,4 +1,6 @@
 from __future__ import annotations
+import datetime
+from typing import Optional
 
 import model
 from model import OrderLine
@@ -20,3 +22,26 @@ def allocate(line: OrderLine, repo: AbstractRepository, session) -> str:
     batchref = model.allocate(line, batches)
     session.commit()
     return batchref
+
+def deallocate(order_id:str, sku:str, repo:AbstractRepository,session):
+
+    order_line = repo.get_line_item(order_id, sku)
+
+    if not order_line :
+        raise Exception("Couldnt find the order line")
+
+    batches = repo.list()
+
+    for batch in batches:
+        if order_line in batch._allocations:
+            batch.deallocate(order_line)
+            break
+    else:
+        raise Exception("Couldnt find the order line in any batch")
+
+    session.commit()
+
+
+def add_batch(ref:str, sku:str, qty:int, eta:Optional[datetime.date], repo:AbstractRepository, session):
+    repo.add(model.Batch(ref, sku, qty, eta))
+    session.commit()

test_api.py

@@ -55,16 +55,16 @@ def test_unhappy_path_returns_400_and_error_message():
 
 @pytest.mark.usefixtures("postgres_db")
 @pytest.mark.usefixtures("restart_api")
-def test_deallocate():
+def test_deallocate(add_stock):
     sku, order1, order2 = random_sku(), random_orderid(), random_orderid()
     batch = random_batchref()
-    post_to_add_batch(batch, sku, 100, "2011-01-02")
+    add_stock([(batch, sku, 100, "2011-01-02")])
     url = config.get_api_url()
     # fully allocate
     r = requests.post(
         f"{url}/allocate", json={"orderid": order1, "sku": sku, "qty": 100}
     )
-    assert r.json()["batchid"] == batch
+    assert r.json()["batchref"] == batch
 
     # cannot allocate second order
     r = requests.post(
@@ -87,4 +87,4 @@ def test_deallocate():
         f"{url}/allocate", json={"orderid": order2, "sku": sku, "qty": 100}
     )
     assert r.ok
-    assert r.json()["batchid"] == batch
+    assert r.json()["batchref"] == batch

test_services.py

@@ -1,3 +1,5 @@
+from datetime import date
+
 import pytest
 import model
 import repository
@@ -16,6 +18,13 @@ def get(self, reference):
 
     def list(self):
         return list(self._batches)
+
+    def get_line_item(self, order_id, sku):
+        for batch in self._batches:
+            for line in batch._allocations:
+                if line.orderid == order_id and line.sku == sku:
+                    return line
+        return None
 
 
 class FakeSession:
@@ -61,14 +70,54 @@ def test_deallocate_decrements_available_quantity():
     services.allocate(line, repo, session)
     batch = repo.get(reference="b1")
     assert batch.available_quantity == 90
-    # services.deallocate(...
-    ...
+    services.deallocate(line.orderid, line.sku, repo, session)
+
     assert batch.available_quantity == 100
 
 
 def test_deallocate_decrements_correct_quantity():
-    ...  #  TODO - check that we decrement the right sku
+    """Among batches with the same SKU, earliest ETA wins; deallocate must target that batch."""
+    repo, session = FakeRepository([]), FakeSession()
+    services.add_batch("b1", "BLUE-PLINTH", 100, date(2011, 1, 1), repo, session)
+    services.add_batch("b2", "BLUE-PLINTH", 100, date(2011, 1, 2), repo, session)
+    services.add_batch("b3", "RED-PLINTH", 100, None, repo, session)
+    line = model.OrderLine("o1", "BLUE-PLINTH", 10)
+    services.allocate(line, repo, session)
+    batch_b1 = repo.get(reference="b1")
+    assert batch_b1.available_quantity == 90
+    services.deallocate(line.orderid, line.sku, repo, session)
+
+    assert batch_b1.available_quantity == 100
+
+
+def test_deallocate_needs_sku_when_one_order_has_several_line_items():
+
+    repo, session = FakeRepository([]), FakeSession()
+    services.add_batch("b-blue", "BLUE-PLINTH", 100, None, repo, session)
+    services.add_batch("b-red", "RED-PLINTH", 100, None, repo, session)
+
+    orderid = "ORD-MULTI"
+    line_blue = model.OrderLine(orderid, "BLUE-PLINTH", 10)
+    line_red = model.OrderLine(orderid, "RED-PLINTH", 7)
+
+    services.allocate(line_blue, repo, session)
+    services.allocate(line_red, repo, session)
+
+    batch_blue = repo.get(reference="b-blue")
+    batch_red = repo.get(reference="b-red")
+    assert batch_blue.available_quantity == 90
+    assert batch_red.available_quantity == 93
+
+    services.deallocate(orderid, "BLUE-PLINTH", repo, session)
+
+    assert batch_blue.available_quantity == 100
+    assert batch_red.available_quantity == 93
 
 
 def test_trying_to_deallocate_unallocated_batch():
-    ...  #  TODO: should this error or pass silently? up to you.
+    """Deallocate fails when order line is not allocated to any batch."""
+    repo, session = FakeRepository([]), FakeSession()
+    services.add_batch("b1", "BLUE-PLINTH", 100, None, repo, session)
+    line = model.OrderLine("o1", "BLUE-PLINTH", 10)
+    with pytest.raises(Exception, match="Couldnt find the order line"):
+        services.deallocate(line.orderid, line.sku, repo, session)