🚧 Add topic explorer

backend/tests/conftest.py

@@ -245,6 +245,71 @@ def client(db_session, monkeypatch):
     monkeypatch.setattr(broker_router, "_call_control", _fake_call_control)
     monkeypatch.setattr(system_router, "_call_control", _fake_call_control)
 
+    # The topic explorer talks to the broker via MQTT. Fake the session
+    # registry + publish/retained so the endpoints can be exercised
+    # without a live broker.
+    from app.routers import topics as topics_router
+    from app import explorer as explorer_module
+
+    class FakeSession:
+        def __init__(self, id, username, topic_filter):
+            self.id = id
+            self.username = username
+            self.topic_filter = topic_filter
+
+    class FakeSessions:
+        def __init__(self):
+            self._sessions = {}
+            self._counter = 0
+        def sweep(self):
+            pass
+        def start(self, username, topic_filter):
+            self._counter += 1
+            sid = f"fake-{self._counter}"
+            self._sessions[sid] = FakeSession(sid, username, topic_filter)
+            return self._sessions[sid]
+        def get(self, session_id):
+            if session_id not in self._sessions:
+                raise KeyError(session_id)
+            return self._sessions[session_id]
+        def stop(self, session_id):
+            self._sessions.pop(session_id, None)
+        def stop_all(self):
+            self._sessions.clear()
+
+    fake_sessions = FakeSessions()
+    monkeypatch.setattr(explorer_module, "sessions", fake_sessions)
+
+    def fake_messages_since(session_id, index):
+        return []
+
+    def fake_list_retained(max_results=200, timeout=3.0):
+        return [
+            {
+                "index": 0,
+                "topic": "site/config/level",
+                "qos": 1,
+                "retain": True,
+                "received_at": 12345.0,
+                "payload_b64": "MTIz",
+                "payload_text": "123",
+                "properties": None,
+            }
+        ]
+
+    def fake_publish(topic, payload, qos, retain, timeout=10.0):
+        fake_publish.calls.append((topic, payload, qos, retain))
+
+    fake_publish.calls = []
+    monkeypatch.setattr(explorer_module, "messages_since", fake_messages_since)
+    monkeypatch.setattr(explorer_module, "list_retained", fake_list_retained)
+    monkeypatch.setattr(explorer_module, "publish_message", fake_publish)
+    # The router imports names from the module: patch there too.
+    monkeypatch.setattr(topics_router.explorer, "sessions", fake_sessions)
+    monkeypatch.setattr(topics_router.explorer, "messages_since", fake_messages_since)
+    monkeypatch.setattr(topics_router.explorer, "list_retained", fake_list_retained)
+    monkeypatch.setattr(topics_router.explorer, "publish_message", fake_publish)
+
     with TestClient(main_module.app) as test_client:
         yield test_client