Merge pull request #16424 An error occurred from czgdp1807:issue-16370

* fixed Split layer in ONNXImporter

* added test for fix of split layer

* fixed tests for Split layer

* applied reviews

* updated tests

* fixed paths in tests

modules/dnn/src/onnx/onnx_importer.cpp

@@ -485,16 +485,23 @@ void ONNXImporter::populateNet(Net dstNet)
          }
         else if (layer_type == "Split")
         {
-            DictValue splits = layerParams.get("split");
-            const int numSplits = splits.size();
-            CV_Assert(numSplits > 1);
+            if (layerParams.has("split"))
+            {
+                DictValue splits = layerParams.get("split");
+                const int numSplits = splits.size();
+                CV_Assert(numSplits > 1);
 
-            std::vector<int> slicePoints(numSplits - 1, splits.get<int>(0));
-            for (int i = 1; i < splits.size() - 1; ++i)
+                std::vector<int> slicePoints(numSplits - 1, splits.get<int>(0));
+                for (int i = 1; i < splits.size() - 1; ++i)
+                {
+                    slicePoints[i] = slicePoints[i - 1] + splits.get<int>(i - 1);
+                }
+                layerParams.set("slice_point", DictValue::arrayInt(&slicePoints[0], slicePoints.size()));
+            }
+            else
             {
-                slicePoints[i] = slicePoints[i - 1] + splits.get<int>(i - 1);
+                layerParams.set("num_split", node_proto.output_size());
             }
-            layerParams.set("slice_point", DictValue::arrayInt(&slicePoints[0], slicePoints.size()));
             layerParams.type = "Slice";
         }
         else if (layer_type == "Add" || layer_type == "Sum")

modules/dnn/test/test_onnx_importer.cpp

@@ -386,6 +386,18 @@ TEST_P(Test_ONNX_layers, ReduceL2)
     testONNXModels("reduceL2");
 }
 
+TEST_P(Test_ONNX_layers, Split)
+{
+    if (backend == DNN_BACKEND_INFERENCE_ENGINE_NN_BUILDER_2019)
+        applyTestTag(CV_TEST_TAG_DNN_SKIP_IE_NN_BUILDER);
+    if (backend == DNN_BACKEND_INFERENCE_ENGINE_NGRAPH)
+        applyTestTag(CV_TEST_TAG_DNN_SKIP_IE_NGRAPH);
+    testONNXModels("split_1");
+    testONNXModels("split_2");
+    testONNXModels("split_3");
+    testONNXModels("split_4");
+}
+
 TEST_P(Test_ONNX_layers, Slice)
 {
 #if defined(INF_ENGINE_RELEASE) && INF_ENGINE_VER_MAJOR_LT(2019010000)