chore: import upstream snapshot with attribution

tests/unittests/workflow/test_workflow_output_deduplication.py

@@ -0,0 +1,161 @@
+# 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 nested workflow output event deduplication.
+
+Verifies that nested workflows produce only leaf terminal events and
+resolve output via terminal path resolution from the graph structure.
+"""
+
+from typing import Any
+
+from google.adk.apps.app import App
+from google.adk.events.event import Event
+from google.adk.workflow._workflow import Workflow
+import pytest
+
+from . import testing_utils
+
+
+def _is_checkpoint(event: Event) -> bool:
+  """Returns True if event is an agent state checkpoint or end_of_agent."""
+  if event.actions.agent_state is not None:
+    return True
+  if event.actions.end_of_agent:
+    return True
+  return False
+
+
+def _output_events(events: list[Event]) -> list[Event]:
+  """Returns only events with output data (not checkpoint/state)."""
+  return [e for e in events if not _is_checkpoint(e) and e.output is not None]
+
+
+async def test_two_level_nesting_deduplicates(
+    request,
+):
+  """Two-level nesting emits only the leaf's output event, not finalize events.
+
+  Setup: outer → inner → leaf.
+  Assert: exactly 1 output event from 'outer/inner/leaf', no
+    duplicate finalize events from inner or outer.
+  """
+
+  async def leaf(node_input: Any):
+    return 'leaf_data'
+
+  inner = Workflow(name='inner', edges=[('START', leaf)])
+  outer = Workflow(name='outer', edges=[('START', inner)])
+
+  app = App(name=request.function.__name__, root_agent=outer)
+  runner = testing_utils.InMemoryRunner(app=app)
+  events = await runner.run_async(testing_utils.get_user_content('hi'))
+  out_events = _output_events(events)
+
+  assert len(out_events) == 1
+  assert out_events[0].output == 'leaf_data'
+  assert out_events[0].node_info.path == 'outer@1/inner@1/leaf@1'
+
+
+async def test_nested_with_output_schema_validates_at_read_time(
+    request,
+):
+  """Nested workflow with output_schema validates without emitting extra events.
+
+  Setup: outer → inner(output_schema=str) → leaf.
+  Assert: 1 output event with validated data, no extra finalize event.
+  """
+
+  async def leaf(node_input: Any):
+    return 'raw_data'
+
+  inner = Workflow(
+      name='inner',
+      edges=[('START', leaf)],
+      output_schema=str,
+  )
+  outer = Workflow(name='outer', edges=[('START', inner)])
+
+  app = App(name=request.function.__name__, root_agent=outer)
+  runner = testing_utils.InMemoryRunner(app=app)
+  events = await runner.run_async(testing_utils.get_user_content('hi'))
+  out_events = _output_events(events)
+
+  assert len(out_events) == 1
+  assert out_events[0].output == 'raw_data'
+
+
+async def test_multiple_terminals_in_nested_workflow_raises(
+    request,
+):
+  """Fan-out with no join raises ValueError for multiple terminal outputs.
+
+  Setup: outer → inner → (branch_a, branch_b).
+  Assert: ValueError because inner has two terminal nodes producing output.
+  """
+
+  async def branch_a(node_input: Any):
+    return 'a_out'
+
+  async def branch_b(node_input: Any):
+    return 'b_out'
+
+  inner = Workflow(
+      name='inner',
+      edges=[('START', (branch_a, branch_b))],
+  )
+  outer = Workflow(name='outer', edges=[('START', inner)])
+
+  app = App(name=request.function.__name__, root_agent=outer)
+  runner = testing_utils.InMemoryRunner(app=app)
+
+  with pytest.raises(ValueError, match='multiple terminal nodes'):
+    await runner.run_async(testing_utils.get_user_content('hi'))
+
+
+async def test_non_terminal_output_not_exposed_as_workflow_output(
+    request,
+):
+  """Downstream node receives terminal output, not intermediate node output.
+
+  Setup: outer → inner(step_a → step_b) → consume.
+  Assert: consume receives step_b's 'final' (terminal), not step_a's
+    'intermediate'.
+  """
+
+  async def step_a(node_input: Any):
+    return 'intermediate'
+
+  async def step_b(node_input: str):
+    return 'final'
+
+  inner = Workflow(name='inner', edges=[('START', step_a, step_b)])
+
+  async def consume(node_input: str):
+    return f'got: {node_input}'
+
+  outer = Workflow(name='outer', edges=[('START', inner, consume)])
+
+  app = App(name=request.function.__name__, root_agent=outer)
+  runner = testing_utils.InMemoryRunner(app=app)
+  events = await runner.run_async(testing_utils.get_user_content('hi'))
+  out_events = _output_events(events)
+
+  consume_events = [
+      e
+      for e in out_events
+      if e.node_info.name and e.node_info.name.split('@')[0] == 'consume'
+  ]
+  assert len(consume_events) == 1
+  assert consume_events[0].output == 'got: final'