isolated test for a handler [test_handler_in_isolation]

hjwp · hjwp · commit ddc98b14b665 · 2020-01-03T03:01:00.000Z
diff --git a/tests/unit/test_handlers.py b/tests/unit/test_handlers.py
@@ -138,3 +138,24 @@ def publish_events(self):
         for product in self.products.seen:
             while product.events:
                 self.events_published.append(product.events.pop(0))
+
+
+def test_reallocates_if_necessary_isolated():
+    uow = FakeUnitOfWorkWithFakeMessageBus()
+
+    # test setup as before
+    messagebus.handle(events.BatchCreated("batch1", "INDIFFERENT-TABLE", 50, None), uow)
+    messagebus.handle(events.BatchCreated("batch2", "INDIFFERENT-TABLE", 50, date.today()), uow)
+    messagebus.handle(events.AllocationRequired("order1", "INDIFFERENT-TABLE", 20), uow)
+    messagebus.handle(events.AllocationRequired("order2", "INDIFFERENT-TABLE", 20), uow)
+    [batch1, batch2] = uow.products.get(sku="INDIFFERENT-TABLE").batches
+    assert batch1.available_quantity == 10
+
+    messagebus.handle(events.BatchQuantityChanged("batch1", 25), uow)
+
+    # assert on new events emitted rather than downstream side-effects
+    [reallocation_event] = uow.events_published
+    assert isinstance(reallocation_event, events.AllocationRequired)
+    assert reallocation_event.orderid in {'order1', 'order2'}
+    assert reallocation_event.sku == 'INDIFFERENT-TABLE'
+
