test: Add tests for recursive model equality to prevent infinite recursion

YassinNouh21 · YassinNouh21 · commit 901b43c7476d · 2025-03-19T02:38:14.000+02:00
diff --git a/tests/test_recursive_eq.py b/tests/test_recursive_eq.py
@@ -0,0 +1,76 @@
+from typing import Optional
+
+from pydantic import BaseModel
+
+
+def test_recursive_model_equality():
+    """Test that comparing models with self-references doesn't cause infinite recursion."""
+
+    class RecursiveModel(BaseModel):
+        value: int
+        parent: Optional['RecursiveModel'] = None
+
+    # Create a model with a reference to itself
+    model = RecursiveModel(value=1)
+    model.parent = model
+
+    # This should not cause infinite recursion
+    assert model == model
+
+    # Create another model with the same structure
+    model2 = RecursiveModel(value=1)
+    model2.parent = model2
+
+    # These models should be equal
+    assert model == model2
+
+    # Create a model with a different value
+    model3 = RecursiveModel(value=2)
+    model3.parent = model3
+
+    # These models should not be equal
+    assert model != model3
+
+
+def test_recursive_model_complex_cycle():
+    """Test that comparing models with complex reference cycles doesn't cause infinite recursion."""
+
+    class Node(BaseModel):
+        value: int
+        children: list['Node'] = []
+
+    # Create a cycle: root -> child1 -> child2 -> root
+    root = Node(value=1)
+    child1 = Node(value=2)
+    child2 = Node(value=3)
+
+    root.children = [child1]
+    child1.children = [child2]
+    child2.children = [root]
+
+    # This should not cause infinite recursion
+    assert root == root
+
+    # Create another identical structure
+    root2 = Node(value=1)
+    child1_2 = Node(value=2)
+    child2_2 = Node(value=3)
+
+    root2.children = [child1_2]
+    child1_2.children = [child2_2]
+    child2_2.children = [root2]
+
+    # These should be equal
+    assert root == root2
+
+    # Create a structure with a different value
+    root3 = Node(value=4)
+    child1_3 = Node(value=2)
+    child2_3 = Node(value=3)
+
+    root3.children = [child1_3]
+    child1_3.children = [child2_3]
+    child2_3.children = [root3]
+
+    # These should not be equal
+    assert root != root3
