test: add functional vertical flip tests on segmentation mask (#5860)

* test: add functional vertical flip tests on segmentation mask

* refactor: improve test readibility

* Update test_prototype_transforms_functional.py
Co-authored-by: Federico Pozzi <federico.pozzi@argo.vision>
Co-authored-by: vfdev <vfdev.5@gmail.com>

test/test_prototype_transforms_functional.py

@@ -346,6 +346,12 @@ def crop_segmentation_mask():
         )
 
 
+@register_kernel_info_from_sample_inputs_fn
+def vertical_flip_segmentation_mask():
+    for mask in make_segmentation_masks():
+        yield SampleInput(mask)
+
+
 @pytest.mark.parametrize(
     "kernel",
     [
@@ -915,3 +921,15 @@ def test_correctness_crop_segmentation_mask(device, top, left, height, width):
         output_mask = F.crop_segmentation_mask(mask, top, left, height, width)
         expected_mask = _compute_expected_mask(mask, top, left, height, width)
         torch.testing.assert_close(output_mask, expected_mask)
+
+
+@pytest.mark.parametrize("device", cpu_and_gpu())
+def test_correctness_vertical_flip_segmentation_mask_on_fixed_input(device):
+    mask = torch.zeros((3, 3, 3), dtype=torch.long, device=device)
+    mask[:, 0, :] = 1
+
+    out_mask = F.vertical_flip_segmentation_mask(mask)
+
+    expected_mask = torch.zeros((3, 3, 3), dtype=torch.long, device=device)
+    expected_mask[:, -1, :] = 1
+    torch.testing.assert_close(out_mask, expected_mask)