Resolve "System tests iteration 1"

Closes #62 (closed)

Added test cases for creating and simulating the simple filter used in the first lab for TSTE87. The SFG used in the labs gives output from the SFG as an array, although, our program seems to give these outputs values incrementally. I expect that we will need to change this in the future to be able to plot the output values.

Also refactorized some test cases.

b_asic/signal_flow_graph.py

@@ -367,6 +367,44 @@ class SFG(AbstractOperation):
                             # Add connected operation to the queue of operations to visit.
                             op_stack.append(original_connected_op)
 
+    def replace_component(self, component: Operation, _component: Operation = None, _id: GraphID = None):
+        """Find and replace all components matching either on GraphID, Type or both.
+        Then return a new deepcopy of the sfg with the replaced component.
+
+        Arguments:
+        component: The new component(s), e.g Multiplication
+
+        Keyword arguments:
+        _component: The specific component to replace.
+        _id: The GraphID to match the component to replace.
+        """
+
+        assert _component is not None or _id is not None, \
+            "Define either operation to replace or GraphID of operation"
+
+        if _id is not None:
+            _component = self.find_by_id(_id)
+
+        assert _component is not None and isinstance(_component, Operation), \
+            "No operation matching the criteria found"
+        assert _component.output_count == component.output_count, \
+            "The output count may not differ between the operations"
+        assert _component.input_count == component.input_count, \
+            "The input count may not differ between the operations"
+
+        for index_in, _inp in enumerate(_component.inputs):
+            for _signal in _inp.signals:
+                _signal.remove_destination()
+                _signal.set_destination(component.input(index_in))
+        
+        for index_out, _out in enumerate(_component.outputs):
+            for _signal in _out.signals:
+                _signal.remove_source()
+                _signal.set_source(component.output(index_out))
+
+        # The old SFG will be deleted by Python GC
+        return self()
+
     def _evaluate_source(self, src: OutputPort, results: MutableResultMap, registers: MutableRegisterMap, prefix: str) -> Number:
         src_prefix = prefix
         if src_prefix: