Items added to one cart show up in other carts

Done

/home/devdi/devswarm/evals/tasks/shared_cart_items/repo · 2026-11-09 16:21:23 UTC · took 30.7s

Plan (done)
Code (done)
Test (done)
Review (done)
Finish (done)

Cost

$0.0028

Tests

Passed

Iterations

Re-plans

LLM calls

Prompt read from cache

80%

Usage by agent

Cost per agent

Tokens per agent

Cache read
Cache write
Input
Output

View as table

Agent	Cost	Cache read	Cache write	Input	Output
planner	$0.0006	5,609	718	8	909
coder	$0.0007	8,622	1,806	8	800
tester	$0.0009	9,780	2,533	8	1,066
reviewer	$0.0006	5,180	2,348	6	460

Timeline

planner iteration 1 Finished 3 calls · 7,244 tokens · $0.0006 · 7.8s

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coder iteration 1 Finished 3 calls · 11.2K tokens · $0.0007 · 6.7s

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tester iteration 1 Finished 3 calls · 13.4K tokens · $0.0009 · 9.6s

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verify iteration 1 Passed 0.5s

.......                                                                  [100%]
7 passed in 0.02s

reviewer iteration 1 Finished 2 calls · 7,994 tokens · $0.0006 · 5.4s

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Final diff

diff --git a/cart.py b/cart.py
index bff9b5d..9d4c165 100644
--- a/cart.py
+++ b/cart.py
@@ -1,6 +1,6 @@
 class Cart:
-    def __init__(self, items=[]):
-        self.items = items
+    def __init__(self, items=None):
+        self.items = list(items) if items is not None else []
 
     def add(self, item: str) -> None:
         self.items.append(item)
diff --git a/test_cart.py b/test_cart.py
index 2040527..abffe54 100644
--- a/test_cart.py
+++ b/test_cart.py
@@ -5,3 +5,43 @@ def test_add_and_count():
     cart = Cart(items=["a"])
     cart.add("b")
     assert cart.count() == 2
+
+
+def test_carts_are_independent():
+    cart1 = Cart()
+    cart2 = Cart()
+    cart1.add("a")
+    assert cart1.count() == 1
+    assert cart2.count() == 0
+
+
+def test_input_list_not_mutated():
+    lst = ["a"]
+    cart = Cart(items=lst)
+    cart.add("b")
+    assert lst == ["a"]
+    assert cart.count() == 2
+
+
+def test_empty_cart_count_is_zero():
+    assert Cart().count() == 0
+
+
+def test_explicit_none_gives_empty_cart():
+    cart = Cart(items=None)
+    assert cart.count() == 0
+    cart.add("a")
+    assert cart.count() == 1
+
+
+def test_tuple_items_accepted():
+    cart = Cart(items=("a",))
+    cart.add("b")
+    assert cart.items == ["a", "b"]
+
+
+def test_generator_items_consumed_into_cart():
+    cart = Cart(items=(x for x in ["a", "b"]))
+    assert cart.count() == 2
+    cart.add("c")
+    assert cart.count() == 3