gst-python: Test for GstAnalyticsRelationMeta iterator

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8237>

subprojects/gst-python/testsuite/test_analytics.py

@@ -37,6 +37,7 @@ from gi.repository import Gst
 from gi.repository import GstAnalytics
 from gi.repository import GstVideo
 Gst.init(None)
+GstAnalytics.init()
 
 
 class TestAnalyticsODMtd(TestCase):
@@ -245,3 +246,48 @@ class TestAnalyticsTensorMeta(TestCase):
                                                  GstAnalytics.TensorDimOrder.ROW_MAJOR,
                                                  [0, 2, 5])
         self.assertIsNotNone(tensor3)
+
+
+class TestAnalyticsRelationMetaIterator(TestCase):
+    def test(self):
+        buf = Gst.Buffer()
+        self.assertIsNotNone(buf)
+
+        rmeta = GstAnalytics.buffer_add_analytics_relation_meta(buf)
+        self.assertIsNotNone(rmeta)
+
+        mask_buf = Gst.Buffer.new_allocate(None, 100, None)
+        GstVideo.buffer_add_video_meta(mask_buf,
+                                       GstVideo.VideoFrameFlags.NONE,
+                                       GstVideo.VideoFormat.GRAY8, 10, 10)
+
+        (_, od_mtd) = rmeta.add_od_mtd(GLib.quark_from_string("od"), 1, 1, 2, 2, 0.1)
+        (_, cls_mtd) = rmeta.add_one_cls_mtd(0.1, GLib.quark_from_string("cls"))
+        (_, trk_mtd) = rmeta.add_tracking_mtd(1, 10)
+        (_, seg_mtd) = rmeta.add_segmentation_mtd(mask_buf,
+                                               GstAnalytics.SegmentationType.SEMANTIC,
+                                               [7, 4, 2], 0, 0, 7, 13)
+
+        mtds = [
+            (od_mtd, GstAnalytics.ODMtd.get_mtd_type()),
+            (cls_mtd, GstAnalytics.ClsMtd.get_mtd_type()),
+            (trk_mtd, GstAnalytics.TrackingMtd.get_mtd_type()),
+            (seg_mtd, GstAnalytics.SegmentationMtd.get_mtd_type())
+        ]
+
+        mtds_from_iter = list(rmeta)
+
+        self.assertEqual(len(mtds), len(mtds_from_iter))
+
+        for e, i in zip(mtds, rmeta):
+            assert e[0].id == i.id
+            assert e[0].meta == i.meta
+            assert e[1] == i.get_mtd_type()
+
+        # Validate that the object is really a ODMtd
+        location = mtds_from_iter[0].get_location()
+        self.assertEqual(location[1], 1)
+        self.assertEqual(location[2], 1)
+        self.assertEqual(location[3], 2)
+        self.assertEqual(location[4], 2)
+        self.assertAlmostEqual(location[5], 0.1, 3)