Add anchor check and tests to polygon zone

supervision/detection/line_zone.py

@@ -82,8 +82,8 @@ class LineZone:
         self.tracker_state: Dict[str, bool] = {}
         self.in_count: int = 0
         self.out_count: int = 0
-        self.triggering_anchors = list(triggering_anchors)
-        if not self.triggering_anchors:
+        self.triggering_anchors = triggering_anchors
+        if not list(self.triggering_anchors):
             raise ValueError("Triggering anchors cannot be empty.")
 
     @staticmethod

supervision/detection/tools/polygon_zone.py

@@ -54,6 +54,8 @@ class PolygonZone:
 
         self.polygon = polygon.astype(int)
         self.triggering_anchors = triggering_anchors
+        if not list(self.triggering_anchors):
+            raise ValueError("Triggering anchors cannot be empty.")
 
         self.current_count = 0
 

test/detection/test_polygonzone.py

@@ -92,3 +92,19 @@ def test_polygon_zone_trigger(
     with exception:
         in_zone = polygon_zone.trigger(detections)
         assert np.all(in_zone == expected_results)
+
+
+@pytest.mark.parametrize(
+    "polygon, triggering_anchors, exception",
+    [
+        (POLYGON, [sv.Position.CENTER], DoesNotRaise()),
+        (
+            POLYGON,
+            [],
+            pytest.raises(ValueError),
+        ),
+    ],
+)
+def test_polygon_zone_initialization(polygon, triggering_anchors, exception):
+    with exception:
+        sv.PolygonZone(polygon, FRAME_RESOLUTION, triggering_anchors=triggering_anchors)