dataflow_cpp: added connection chain test

dataflow_cpp/test/dataflow_cpp_test_simple.cc

@@ -189,11 +189,14 @@ void SimpleTest::TestBasic() {
 
     source.GetOutput<0>() >> sw.GetInput<1>();
 
-    source.GetOutput<0>() >> pred.GetInput<0>();
-    pred.GetOutput<0>() >> sw.GetInput<0>();
+    // connection chain representing the commented single connections below
+    source >> pred >> sw >> filter;
+
+    //source.GetOutput<0>() >> pred.GetInput<0>();
+    //pred.GetOutput<0>() >> sw.GetInput<0>();
     pred.GetOutput<0>() >> sel.GetInput<0>();
 
-    sw.GetOutput<0>() >> filter.GetInput<0>();
+    //sw.GetOutput<0>() >> filter.GetInput<0>();
     filter.GetOutput<0>() >> sel.GetInput<1>();
 
     constant.GetOutput<0>() >> mult.GetInput<0>();