Implementation:Googleapis Python genai ReplayApiClient

Knowledge Sources	Googleapis_Python_genai
Domains	Testing, API_Infrastructure
Last Updated	2026-02-15 14:00 GMT

Overview

Concrete tool for recording and replaying API interactions for deterministic testing.

Description

The ReplayApiClient extends BaseApiClient to support record/replay testing modes. In record mode, it captures HTTP interactions to JSON files. In replay mode, it serves responses from recorded files without making actual API calls. It also provides request redaction for sensitive data and case-insensitive request matching.

Usage

Used by the SDK test suite for deterministic, offline testing of API interactions without requiring real API credentials or network access.

Code Reference

Source Location

• Repository: Googleapis_Python_genai
• File: google/genai/_replay_api_client.py
• Lines: 264-671

Signature

class ReplayApiClient(BaseApiClient):
    def __init__(
        self,
        mode: Literal['record', 'replay', 'auto', 'api'],
        replay_id: str,
        replays_directory: Optional[str] = None,
        vertexai: bool = False,
        api_key: Optional[str] = None,
        credentials: Optional[google.auth.credentials.Credentials] = None,
        project: Optional[str] = None,
        location: Optional[str] = None,
        http_options: Optional[HttpOptions] = None,
        private: bool = False,
    ) -> None: ...

    def initialize_replay_session(self, replay_id: str) -> None: ...
    def close(self) -> None: ...

Import

from google.genai._replay_api_client import ReplayApiClient

I/O Contract

Inputs

Name	Type	Required	Description
mode	Literal['record', 'replay', 'auto', 'api']	Yes	Operating mode
replay_id	str	Yes	Unique identifier for the replay session
replays_directory	str	No	Directory for storing replay files
vertexai	bool	No	Whether to use Vertex AI backend

Outputs

Name	Type	Description
_request returns	HttpResponse	Response from API or replay file
close()	None	Writes recorded interactions to replay file

Usage Examples

from google.genai._replay_api_client import ReplayApiClient

# Create a replay client for testing
client = ReplayApiClient(
    mode="replay",
    replay_id="test_generate_content",
    replays_directory="google/genai/tests",
)

# Use the client normally - responses come from recorded files
response = client._request(http_request)

Related Pages

• Environment:Googleapis_Python_genai_Python_3_10_SDK_Runtime