--- a
+++ b/tests/test_utils/test_onnx.py
@@ -0,0 +1,32 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+import os.path as osp
+import tempfile
+
+import torch.nn as nn
+from tools.deployment.pytorch2onnx import _convert_batchnorm, pytorch2onnx
+
+
+class TestModel(nn.Module):
+
+    def __init__(self):
+        super().__init__()
+        self.conv = nn.Conv3d(1, 2, 1)
+        self.bn = nn.SyncBatchNorm(2)
+
+    def forward(self, x):
+        return self.bn(self.conv(x))
+
+    def forward_dummy(self, x):
+        out = self.bn(self.conv(x))
+        return (out, )
+
+
+def test_onnx_exporting():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        out_file = osp.join(tmpdir, 'tmp.onnx')
+        model = TestModel()
+        model = _convert_batchnorm(model)
+        # test exporting
+        if hasattr(model, 'forward_dummy'):
+            model.forward = model.forward_dummy
+        pytorch2onnx(model, (2, 1, 1, 1, 1), output_file=out_file, verify=True)