TST: added a test for order of sync nodes in lists

unittests/test_sync_node.py

@@ -260,8 +260,9 @@ def test_export_node():
 
     exp = SyncNode(rec_a).export_entity()
     assert exp.get_property('a').value.id == 1
+    assert len([p for p in exp.properties if p.name == "a"]) == 1
 
-    # different SyncNode Objects are not equal
+    # different SyncNode Objects (without an ID) are not equal
     rec_a = (db.Record(id=101)
              .add_parent("B")
              .add_property(name="a", value=SyncNode(db.Record()))
@@ -270,7 +271,7 @@ def test_export_node():
     with pytest.raises(ImpossibleMergeError):
         exp = SyncNode(rec_a).export_entity()
 
-    # different SyncNode Objects with differing are not equal
+    # different SyncNode Objects with differing ID are not equal
     rec_a = (db.Record(id=101)
              .add_parent("B")
              .add_property(name="a", value=SyncNode(db.Record(id=1)))
@@ -287,6 +288,16 @@ def test_export_node():
 
     exp = SyncNode(rec_a).export_entity()
     assert exp.get_property('a').value[0].id == 1
+    assert len([p for p in exp.properties if p.name == "a"]) == 1
+
+    # SyncNodes with same ID are not equal when in different order (list)
+    rec_a = (db.Record(id=101)
+             .add_parent("B")
+             .add_property(name="a", value=[SyncNode(db.Record(id=1)), SyncNode(db.Record(id=2))])
+             .add_property(name="a", value=[SyncNode(db.Record(id=2)), SyncNode(db.Record(id=1))]))
+
+    with pytest.raises(ImpossibleMergeError):
+        exp = SyncNode(rec_a).export_entity()
 
     # same SyncNode object is obviously equal (list)
     sn = SyncNode(db.Record(id=1))