test allocate twice [last_test]

Author: hjwp

test_batches.py

@@ -1,6 +1,5 @@
 from datetime import date
 from model import Batch, OrderLine
-from datetime import date
 
 
 def test_allocating_to_a_batch_reduces_the_available_quantity():
@@ -36,6 +35,13 @@ def test_cannot_allocate_if_skus_do_not_match():
     assert batch.can_allocate(different_sku_line) is False
 
 
+def test_allocation_is_idempotent():
+    batch, line = make_batch_and_line("ANGULAR-DESK", 20, 2)
+    batch.allocate(line)
+    batch.allocate(line)
+    assert batch.available_quantity == 18
+
+
 def test_deallocate():
     batch, line = make_batch_and_line("EXPENSIVE-FOOTSTOOL", 20, 2)
     batch.allocate(line)