Harden GPS mode updates with callback reattach and status polling fallback

tests/test_gps_routes.py

@@ -0,0 +1,63 @@
+"""Tests for GPS route behavior and gps client callback management."""
+
+from routes import gps as gps_routes
+from utils.gps import GPSDClient
+
+
+def test_gpsd_client_add_callback_deduplicates():
+    """Adding the same position callback twice should only register once."""
+    client = GPSDClient()
+
+    def callback(_position):
+        return None
+
+    client.add_callback(callback)
+    client.add_callback(callback)
+
+    assert client._callbacks.count(callback) == 1
+
+
+def test_gpsd_client_add_sky_callback_deduplicates():
+    """Adding the same sky callback twice should only register once."""
+    client = GPSDClient()
+
+    def callback(_sky):
+        return None
+
+    client.add_sky_callback(callback)
+    client.add_sky_callback(callback)
+
+    assert client._sky_callbacks.count(callback) == 1
+
+
+def test_auto_connect_attaches_callbacks_when_reader_already_running(client, monkeypatch):
+    """Auto-connect should re-attach stream callbacks for an already-running reader."""
+
+    class FakeReader:
+        is_running = True
+        position = None
+        sky = None
+
+        def __init__(self):
+            self.position_callbacks = []
+            self.sky_callbacks = []
+
+        def add_callback(self, callback):
+            self.position_callbacks.append(callback)
+
+        def add_sky_callback(self, callback):
+            self.sky_callbacks.append(callback)
+
+    reader = FakeReader()
+    monkeypatch.setattr(gps_routes, 'get_gps_reader', lambda: reader)
+
+    with client.session_transaction() as sess:
+        sess['logged_in'] = True
+
+    response = client.post('/gps/auto-connect')
+    payload = response.get_json()
+
+    assert response.status_code == 200
+    assert payload['status'] == 'connected'
+    assert reader.position_callbacks == [gps_routes._position_callback]
+    assert reader.sky_callbacks == [gps_routes._sky_callback]