Fix bug in GraphFlow cycle check (#6629)

Resolve #6628

python/packages/autogen-agentchat/src/autogen_agentchat/teams/_group_chat/_graph/_digraph_group_chat.py

@@ -159,7 +159,7 @@ class DiGraph(BaseModel):
                     cycle_edges: List[DiGraphEdge] = []
                     for n in cycle_nodes:
                         cycle_edges.extend(self.nodes[n].edges)
-                    if not any(edge.condition is not None for edge in cycle_edges):
+                    if all(edge.condition is None and edge.condition_function is None for edge in cycle_edges):
                         raise ValueError(
                             f"Cycle detected without exit condition: {' -> '.join(cycle_nodes + cycle_nodes[:1])}"
                         )

python/packages/autogen-agentchat/tests/test_group_chat_graph.py

@@ -219,6 +219,18 @@ def test_cycle_detection_with_exit_condition() -> None:
     )
     assert graph.has_cycles_with_exit()
 
+    # Use a lambda condition
+    graph_with_lambda = DiGraph(
+        nodes={
+            "A": DiGraphNode(name="A", edges=[DiGraphEdge(target="B")]),
+            "B": DiGraphNode(name="B", edges=[DiGraphEdge(target="C")]),
+            "C": DiGraphNode(
+                name="C", edges=[DiGraphEdge(target="A", condition=lambda msg: "test" in msg.to_model_text())]
+            ),  # Cycle with lambda
+        }
+    )
+    assert graph_with_lambda.has_cycles_with_exit()
+
 
 def test_cycle_detection_without_exit_condition() -> None:
     """Test that cycle without exit condition raises an error."""