refactor: ZMQ context and proxy

Use ZMQ's global context instance and setup an XPUB/XSUB proxy intermediary to allow for easier multi-pubs.

close: N25B-217

test/integration/api/endpoints/test_command_endpoint.py

@@ -1,7 +1,8 @@
+from unittest.mock import AsyncMock, patch
+
 import pytest
 from fastapi import FastAPI
 from fastapi.testclient import TestClient
-from unittest.mock import MagicMock
 
 from control_backend.api.v1.endpoints import command
 from control_backend.schemas.ri_message import SpeechCommand
@@ -15,7 +16,6 @@ def app():
     """
     app = FastAPI()
     app.include_router(command.router)
-    app.state.internal_comm_socket = MagicMock()  # mock ZMQ socket
     return app
 
 
@@ -25,12 +25,42 @@ def client(app):
     return TestClient(app)
 
 
-def test_receive_command_endpoint(client, app):
+@pytest.mark.asyncio
+@patch("control_backend.api.endpoints.command.Context.instance")
+async def test_receive_command_success(mock_context_instance, async_client):
+    """
+    Test for successful reception of a command.
+    Ensures the status code is 202 and the response body is correct.
+    It also verifies that the ZeroMQ socket's send_multipart method is called with the expected data.
+    """
+    # Arrange
+    mock_pub_socket = AsyncMock()
+    mock_context_instance.return_value.socket.return_value = mock_pub_socket
+
+    command_data = {"command": "test_command", "text": "This is a test"}
+    speech_command = SpeechCommand(**command_data)
+
+    # Act
+    response = await async_client.post("/command", json=command_data)
+
+    # Assert
+    assert response.status_code == 202
+    assert response.json() == {"status": "Command received"}
+
+    # Verify that the ZMQ socket was used correctly
+    mock_context_instance.return_value.socket.assert_called_once_with(1)  # zmq.PUB is 1
+    mock_pub_socket.connect.assert_called_once()
+    mock_pub_socket.send_multipart.assert_awaited_once_with(
+        [b"command", speech_command.model_dump_json().encode()]
+    )
+
+
+def test_receive_command_endpoint(client, app, mocker):
     """
     Test that a POST to /command sends the right multipart message
     and returns a 202 with the expected JSON body.
     """
-    mock_socket = app.state.internal_comm_socket
+    mock_socket = mocker.patch.object()
 
     # Prepare test payload that matches SpeechCommand
     payload = {"endpoint": "actuate/speech", "data": "yooo"}