test deallocate not allocated [test_deallocate_unallocated]

Author: hjwp

test_batches.py

@@ -41,3 +41,9 @@ def test_deallocate():
     batch.allocate(line)
     batch.deallocate(line)
     assert batch.available_quantity == 20
+
+
+def test_can_only_deallocate_allocated_lines():
+    batch, unallocated_line = make_batch_and_line("DECORATIVE-TRINKET", 20, 2)
+    batch.deallocate(unallocated_line)
+    assert batch.available_quantity == 20