test_client.py

import os
from slack_sdk.web import WebClient
from slack_sdk.socket_mode import SocketModeClient

# Initialize SocketModeClient with an app-level token + WebClient
client = SocketModeClient(
    # This app-level token will be used only for establishing a connection
    app_token=os.environ.get("SLACK_APP_TOKEN")
    # You will be using this WebClient for performing Web API calls in listeners
    web_client=WebClient(token=os.environ.get("SLACK_BOT_TOKEN"))  # xoxb-111-222-xyz
)

from slack_sdk.socket_mode.response import SocketModeResponse
from slack_sdk.socket_mode.request import SocketModeRequest

def process(client: SocketModeClient, req: SocketModeRequest):
    print('here')
    if req.type == "events_api":
        # Acknowledge the request anyway
        response = SocketModeResponse(envelope_id=req.envelope_id)
        client.send_socket_mode_response(response)

        # Add a reaction to the message if it's a new message
        if req.payload["event"]["type"] == "message" \
            and req.payload["event"].get("subtype") is None:
            client.web_client.reactions_add(
                name="eyes",
                channel=req.payload["event"]["channel"],
                timestamp=req.payload["event"]["ts"],
            )

# Add a new listener to receive messages from Slack
# You can add more listeners like this
client.socket_mode_request_listeners.append(process)
# Establish a WebSocket connection to the Socket Mode servers
client.connect()
# Just not to stop this process
from threading import Event
Event().wait()