Add test for type upcasting.

src/ngraph/type.hpp

@@ -42,7 +42,8 @@ namespace ngraph
         
         /**
          ** Unmanaged cast to a supertype. dynamic_cast cannot be used
-         ** directly on a shared_ptr.
+         ** directly on a shared_ptr. Can use dynamic_pointer_cast if
+         ** a shared_ptr is needed.
          **/ 
         template<typename T> T as() { return dynamic_cast<T>(this); }
     };

test/build_graph.cpp

@@ -19,7 +19,7 @@
 using namespace std;
 using namespace ngraph;
 
-TEST(ngraph, build_simple)
+TEST(build_graph, build_simple)
 {
     // Function with 4 parameters
     auto cluster_0 = make_shared<Function>(4);
@@ -42,3 +42,21 @@ TEST(ngraph, build_simple)
 
     ASSERT_EQ(cluster_0->result()->value(), dot);
 }
+
+// Check upcasting from ValueType.
+TEST(build_graph, as_type)
+{
+    // Check upcasting a ValueType::ptr that is a TensorViewType to a TensorViewType and Tuple.
+    ValueType::ptr tv_vt = make_shared<TensorViewType>(element::float32_t, Shape{2, 3, 5});
+    TensorViewType* tv_tv = tv_vt->as<TensorViewType*>();
+    ASSERT_EQ(tv_vt.get(), tv_tv);
+    TupleType* tv_tp = tv_vt->as<TupleType*>();
+    ASSERT_EQ(nullptr, tv_tp);
+
+    // Check upcasting a ValueType::ptr that is a TupleType to a TensorViewType and Tuple.
+    ValueType::ptr tp_vt = make_shared<TupleType>(vector<ValueType::ptr>{tv_vt, tv_vt});
+    TensorViewType* tp_tv = tp_vt->as<TensorViewType*>();
+    ASSERT_EQ(nullptr, tp_tv);
+    TupleType* tp_tp = tp_vt->as<TupleType*>();
+    ASSERT_EQ(tp_vt.get(), tp_tp);
+}