chore: import upstream snapshot with attribution

tests/unittests/workflow/test_graph.py

@@ -0,0 +1,96 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Tests for Graph validation and routing."""
+
+import logging
+
+from google.adk.workflow import Edge
+from google.adk.workflow import START
+from google.adk.workflow._graph import DEFAULT_ROUTE
+from google.adk.workflow._graph import Graph
+
+from .workflow_testing_utils import TestingNode
+
+
+def test_valid_graph() -> None:
+  """Tests that a valid graph passes validation."""
+  node_a = TestingNode(name='NodeA')
+  graph = Graph(
+      edges=[
+          Edge(from_node=START, to_node=node_a),
+      ],
+  )
+  graph.validate_graph()  # Should not raise
+
+
+def test_get_next_pending_nodes() -> None:
+  """Tests that get_next_pending_nodes returns correct nodes based on routes."""
+  node_a = TestingNode(name='NodeA')
+  node_b = TestingNode(name='NodeB')
+  node_c = TestingNode(name='NodeC')
+  node_d = TestingNode(name='NodeD')
+
+  graph = Graph(
+      edges=[
+          Edge(from_node=node_a, to_node=node_b),  # Unconditional
+          Edge(from_node=node_a, to_node=node_c, route='route1'),  # Conditional
+          Edge(
+              from_node=node_a, to_node=node_d, route=DEFAULT_ROUTE
+          ),  # Default
+      ],
+  )
+
+  # Test unconditional edge triggered
+  next_nodes = graph.get_next_pending_nodes('NodeA', routes_to_match=None)
+  assert set(next_nodes) == {'NodeB', 'NodeD'}
+
+  # Test specific route matched
+  next_nodes = graph.get_next_pending_nodes('NodeA', routes_to_match='route1')
+  assert set(next_nodes) == {'NodeB', 'NodeC'}
+
+  # Test unmatched route falls back to default
+  next_nodes = graph.get_next_pending_nodes(
+      'NodeA', routes_to_match='unknown_route'
+  )
+  assert set(next_nodes) == {'NodeB', 'NodeD'}
+
+  # Test list of routes to match
+  next_nodes = graph.get_next_pending_nodes(
+      'NodeA', routes_to_match=['route1', 'unknown_route']
+  )
+  assert set(next_nodes) == {'NodeB', 'NodeC'}
+
+
+def test_get_next_pending_nodes_unmatched_route_warning(caplog) -> None:
+  """Tests that a warning is logged when a route is unmatched and there's no DEFAULT_ROUTE."""
+  node_a = TestingNode(name='NodeA')
+  node_c = TestingNode(name='NodeC')
+
+  graph = Graph(
+      edges=[
+          Edge(from_node=node_a, to_node=node_c, route='route1'),
+      ],
+  )
+
+  with caplog.at_level(logging.WARNING):
+    next_nodes = graph.get_next_pending_nodes(
+        'NodeA', routes_to_match='unknown_route'
+    )
+
+  assert not next_nodes
+  assert any(
+      'has conditional/DEFAULT edges but none were matched' in record.message
+      for record in caplog.records
+  )