[ONNX] Import functions input validation (#2475)

src/ngraph/frontend/onnx_import/onnx.cpp

@@ -35,7 +35,7 @@ namespace ngraph
                 struct file_open : ngraph_error
                 {
                     explicit file_open(const std::string& path)
-                        : ngraph_error{"failure opening file:" + path}
+                        : ngraph_error{"Failure opening file: " + path}
                     {
                     }
                 };
@@ -43,7 +43,7 @@ namespace ngraph
                 struct stream_parse : ngraph_error
                 {
                     explicit stream_parse(std::istream&)
-                        : ngraph_error{"failure parsing data from the stream"}
+                        : ngraph_error{"Failure parsing data from the provided input stream"}
                     {
                     }
                 };

test/models/onnx/malformed.onnx

+ngraph ONNXImporter:D
+
+x
y"Sign
+ign_graphZ
+x
+

+

+b
+y
+

+

+B

test/onnx_import.in.cpp

@@ -2030,3 +2030,29 @@ TEST(onnx_${BACKEND_NAME}, model_where)
 
     EXPECT_EQ(expected_outputs.front(), outputs.front());
 }
+
+TEST(onnx_${BACKEND_NAME}, import_non_existing_file)
+{
+    try
+    {
+        onnx_import::import_onnx_model(file_util::path_join(SERIALIZED_ZOO, "onnx/i.dont.exist"));
+    }
+    catch (const std::runtime_error& exc)
+    {
+        // asserts that an exception was thrown and that the error message contains the file name
+        std::string msg{exc.what()};
+        EXPECT_TRUE(msg.find("i.dont.exist") != std::string::npos);
+    }
+}
+
+TEST(onnx_${BACKEND_NAME}, import_malformed_model)
+{
+    try
+    {
+        onnx_import::import_onnx_model(file_util::path_join(SERIALIZED_ZOO, "onnx/malformed.onnx"));
+    }
+    catch (const std::runtime_error& exc)
+    {
+        EXPECT_EQ(exc.what(), std::string{"Failure parsing data from the provided input stream"});
+    }
+}