Feat/public testing utilities

[alexbond85]

Summary

Exposed internal testing utilities as public API in google.adk.testing module for PyPI distribution.

What Was Done

Created src/google/adk/testing/ module:

• testing_utils.py - Core utilities (MockModel, InMemoryRunner, TestInMemoryRunner, helper functions)
• __init__.py - Public API exports

Modified tests/unittests/testing_utils.py:

• Now re-exports from public module for backward compatibility

Key APIs

• MockModel - Returns predefined responses without LLM API calls
• InMemoryRunner - Runs agents with in-memory services
• TestInMemoryRunner - Async-focused test runner
• Helper functions: create_test_agent(), simplify_events(), create_invocation_context()

Usage

from google.adk.testing import MockModel, InMemoryRunner

agent = Agent(
    name="test",
    model=MockModel.create(responses=["test response"]),
    instruction="test instruction"
)

runner = InMemoryRunner(root_agent=agent)
events = runner.run("input")

Compatibility

No breaking changes - all existing tests work unchanged.

Testing Plan

uv sync --extra test --extra eval --extra a2a && pytest tests/unittests - all tests run successfully

Associated Issue

Decided not to raise and issue, implemented it directly instead

[adk-bot]

Response from ADK Triaging Agent

Hello @alexbond85, thank you for your contribution!

To help us review this PR, could you please address the following points from our contribution guidelines?

• Associated Issue: For new features, please create an issue that describes the feature and associate it with this PR.
• Testing Plan: Please add a "Testing Plan" section to your PR description explaining how you have tested these changes.

You can find more details in our contribution guidelines.

Thank you!

[ryanaiagent]

Hi @alexbond85, Thank you for your contribution! We appreciate you taking the time to submit this pull request.
Before we proceed with the review can you fix the failing tests.

[alexbond85]

@ryanaiagent done

[ryanaiagent]

Hi @DeanChensj , can you please review this.