[core] move duplicateNode methods to core.graph

handle this low-level operation engine side

* fix ListAttribute children links duplication
* handle CompatibilityNode duplication
* move corresponding unit test in test_graph.py
* [ui] add DuplicateNodeCommand

tests/test_graph.py

@@ -204,3 +204,33 @@ def test_graph_nodes_sorting():
     ls1 = graph.addNewNode('Ls', name='Ls_1')
 
     assert graph.nodesByType('Ls', sortedByIndex=True) == [ls0, ls1, ls2]
+
+
+def test_duplicate_nodes():
+    """
+    Test nodes duplication.
+    """
+
+    # n0 -- n1 -- n2
+    #   \          \
+    #    ---------- n3
+
+    g = Graph('')
+    n0 = g.addNewNode('Ls', input='/tmp')
+    n1 = g.addNewNode('Ls', input=n0.output)
+    n2 = g.addNewNode('Ls', input=n1.output)
+    n3 = g.addNewNode('AppendFiles', input=n1.output, input2=n2.output)
+
+    # duplicate from n1
+    nMap = g.duplicateNodesFromNode(fromNode=n1)
+    for s, d in nMap.items():
+        assert s.nodeType == d.nodeType
+
+    # check number of duplicated nodes
+    assert len(nMap) == 3
+
+    # check connections
+    assert nMap[n1].input.getLinkParam() == n0.output
+    assert nMap[n2].input.getLinkParam() == nMap[n1].output
+    assert nMap[n3].input.getLinkParam() == nMap[n1].output
+    assert nMap[n3].input2.getLinkParam() == nMap[n2].output