Add test adding the output of two SFGs

test/test_sfg.py

@@ -956,8 +956,8 @@ class TestConnectExternalSignalsToComponentsMultipleComp:
         in2 = Input()
 
         output = Output(c1_sfg + c2_sfg)
-        c1_sfg.input(0).connect(in1)
-        c2_sfg.input(0).connect(in2)
+        c1_sfg << in1
+        c2_sfg << in2
 
         sfg = SFG([in1, in2], [output])
         assert not sfg.find_by_type_name(ConstantMultiplication.type_name())