adk-python/tests/unittests/flows/llm_flows/test_tool_callbacks.py

# Copyright 2025 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.

from typing import Any

from google.adk.agents import Agent
from google.adk.tools import BaseTool
from google.adk.tools import ToolContext
from google.genai import types
from google.genai.types import Part
from pydantic import BaseModel

from ... import utils


def simple_function(input_str: str) -> str:
  return {'result': input_str}


class MockBeforeToolCallback(BaseModel):
  mock_response: dict[str, object]
  modify_tool_request: bool = False

  def __call__(
      self,
      tool: BaseTool,
      args: dict[str, Any],
      tool_context: ToolContext,
  ) -> dict[str, object]:
    if self.modify_tool_request:
      args['input_str'] = 'modified_input'
      return None
    return self.mock_response


class MockAfterToolCallback(BaseModel):
  mock_response: dict[str, object]
  modify_tool_request: bool = False
  modify_tool_response: bool = False

  def __call__(
      self,
      tool: BaseTool,
      args: dict[str, Any],
      tool_context: ToolContext,
      tool_response: dict[str, Any] = None,
  ) -> dict[str, object]:
    if self.modify_tool_request:
      args['input_str'] = 'modified_input'
      return None
    if self.modify_tool_response:
      tool_response['result'] = 'modified_output'
      return tool_response
    return self.mock_response


def noop_callback(
    **kwargs,
) -> dict[str, object]:
  pass


def test_before_tool_callback():
  responses = [
      types.Part.from_function_call(name='simple_function', args={}),
      'response1',
  ]
  mock_model = utils.MockModel.create(responses=responses)
  agent = Agent(
      name='root_agent',
      model=mock_model,
      before_tool_callback=MockBeforeToolCallback(
          mock_response={'test': 'before_tool_callback'}
      ),
      tools=[simple_function],
  )

  runner = utils.InMemoryRunner(agent)
  assert utils.simplify_events(runner.run('test')) == [
      ('root_agent', Part.from_function_call(name='simple_function', args={})),
      (
          'root_agent',
          Part.from_function_response(
              name='simple_function', response={'test': 'before_tool_callback'}
          ),
      ),
      ('root_agent', 'response1'),
  ]


def test_before_tool_callback_noop():
  responses = [
      types.Part.from_function_call(
          name='simple_function', args={'input_str': 'simple_function_call'}
      ),
      'response1',
  ]
  mock_model = utils.MockModel.create(responses=responses)
  agent = Agent(
      name='root_agent',
      model=mock_model,
      before_tool_callback=noop_callback,
      tools=[simple_function],
  )

  runner = utils.InMemoryRunner(agent)
  assert utils.simplify_events(runner.run('test')) == [
      (
          'root_agent',
          Part.from_function_call(
              name='simple_function', args={'input_str': 'simple_function_call'}
          ),
      ),
      (
          'root_agent',
          Part.from_function_response(
              name='simple_function',
              response={'result': 'simple_function_call'},
          ),
      ),
      ('root_agent', 'response1'),
  ]


def test_before_tool_callback_modify_tool_request():
  responses = [
      types.Part.from_function_call(name='simple_function', args={}),
      'response1',
  ]
  mock_model = utils.MockModel.create(responses=responses)
  agent = Agent(
      name='root_agent',
      model=mock_model,
      before_tool_callback=MockBeforeToolCallback(
          mock_response={'test': 'before_tool_callback'},
          modify_tool_request=True,
      ),
      tools=[simple_function],
  )

  runner = utils.InMemoryRunner(agent)
  assert utils.simplify_events(runner.run('test')) == [
      ('root_agent', Part.from_function_call(name='simple_function', args={})),
      (
          'root_agent',
          Part.from_function_response(
              name='simple_function',
              response={'result': 'modified_input'},
          ),
      ),
      ('root_agent', 'response1'),
  ]


def test_after_tool_callback():
  responses = [
      types.Part.from_function_call(
          name='simple_function', args={'input_str': 'simple_function_call'}
      ),
      'response1',
  ]
  mock_model = utils.MockModel.create(responses=responses)
  agent = Agent(
      name='root_agent',
      model=mock_model,
      after_tool_callback=MockAfterToolCallback(
          mock_response={'test': 'after_tool_callback'}
      ),
      tools=[simple_function],
  )

  runner = utils.InMemoryRunner(agent)
  assert utils.simplify_events(runner.run('test')) == [
      (
          'root_agent',
          Part.from_function_call(
              name='simple_function', args={'input_str': 'simple_function_call'}
          ),
      ),
      (
          'root_agent',
          Part.from_function_response(
              name='simple_function', response={'test': 'after_tool_callback'}
          ),
      ),
      ('root_agent', 'response1'),
  ]


def test_after_tool_callback_noop():
  responses = [
      types.Part.from_function_call(
          name='simple_function', args={'input_str': 'simple_function_call'}
      ),
      'response1',
  ]
  mock_model = utils.MockModel.create(responses=responses)
  agent = Agent(
      name='root_agent',
      model=mock_model,
      after_tool_callback=noop_callback,
      tools=[simple_function],
  )

  runner = utils.InMemoryRunner(agent)
  assert utils.simplify_events(runner.run('test')) == [
      (
          'root_agent',
          Part.from_function_call(
              name='simple_function', args={'input_str': 'simple_function_call'}
          ),
      ),
      (
          'root_agent',
          Part.from_function_response(
              name='simple_function',
              response={'result': 'simple_function_call'},
          ),
      ),
      ('root_agent', 'response1'),
  ]


def test_after_tool_callback_modify_tool_response():
  responses = [
      types.Part.from_function_call(
          name='simple_function', args={'input_str': 'simple_function_call'}
      ),
      'response1',
  ]
  mock_model = utils.MockModel.create(responses=responses)
  agent = Agent(
      name='root_agent',
      model=mock_model,
      after_tool_callback=MockAfterToolCallback(
          mock_response={'result': 'after_tool_callback'},
          modify_tool_response=True,
      ),
      tools=[simple_function],
  )

  runner = utils.InMemoryRunner(agent)
  assert utils.simplify_events(runner.run('test')) == [
      (
          'root_agent',
          Part.from_function_call(
              name='simple_function', args={'input_str': 'simple_function_call'}
          ),
      ),
      (
          'root_agent',
          Part.from_function_response(
              name='simple_function',
              response={'result': 'modified_output'},
          ),
      ),
      ('root_agent', 'response1'),
  ]