[core] Add Graph.copy method

Add a new method to create a copy of a graph instance, relying on
chaining serialization and deserialization operations.
Add test suite to validate its behavior, and the underlying serialization processes.

meshroom/core/graph.py

@@ -1345,6 +1345,12 @@ def toDict(self):
     def asString(self):
         return str(self.toDict())
 
+    def copy(self) -> "Graph":
+        """Create a copy of this Graph instance."""
+        graph = Graph("")
+        graph._deserialize(self.serialize())
+        return graph
+
     def serialize(self, asTemplate: bool = False) -> dict:
         """Serialize this Graph instance.
         

tests/test_graphIO.py

@@ -214,3 +214,30 @@ def test_serializeSingleNodeWithInputConnection(self):
             assert len(otherGraph.compatibilityNodes) == 0
             assert len(otherGraph.nodes) == 1
             assert len(otherGraph.edges) == 0
+
+
+class TestGraphCopy:
+    def test_graphCopyIsIdenticalToOriginalGraph(self):
+        graph = Graph("")
+
+        with registeredNodeTypes([SimpleNode]):
+            nodeA = graph.addNewNode(SimpleNode.__name__)
+            nodeB = graph.addNewNode(SimpleNode.__name__)
+
+            graph.addEdge(nodeA.output, nodeB.input)
+
+            graphCopy = graph.copy()
+            assert compareGraphsContent(graph, graphCopy)
+
+    def test_graphCopyWithUnknownNodeTypesDiffersFromOriginalGraph(self):
+        graph = Graph("")
+
+        with registeredNodeTypes([SimpleNode]):
+            nodeA = graph.addNewNode(SimpleNode.__name__)
+            nodeB = graph.addNewNode(SimpleNode.__name__)
+
+            graph.addEdge(nodeA.output, nodeB.input)
+
+        graphCopy = graph.copy()
+        assert not compareGraphsContent(graph, graphCopy)
+