support empty groups

Author: PythonFZ

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "znflow"
-version = "0.2.1"
+version = "0.2.2"
 description = "A general purpose framework for building and running computational graphs."
 authors = ["zincwarecode <[email protected]>"]
 license = "Apache-2.0"

tests/test_graph_group.py

@@ -276,3 +276,24 @@ def test_grp_nodes():
     assert grp.nodes == [n1, n2]
     assert grp.uuids == [n1.uuid, n2.uuid]
     assert grp.names == ("grp1",)
+
+
+def test_empty_grps():
+    graph = znflow.DiGraph()
+
+    with graph.group("grp1") as grp1:
+        pass
+    with graph.group("grp2") as grp2:
+        pass
+
+    assert len(grp1) == 0
+    assert len(grp2) == 0
+    assert grp1.uuids == []
+    assert grp2.uuids == []
+
+    assert grp1.names == ("grp1",)
+    assert grp2.names == ("grp2",)
+
+    assert len(graph.groups) == 2
+    assert grp1.names in graph.groups
+    assert grp2.names in graph.groups

znflow/graph.py

@@ -247,9 +247,9 @@ def group(self, *names: str) -> typing.Generator[Group, None, None]:
         group = self.groups.get(names, Group(names=names, uuids=[], graph=self))
 
         def finalize_group():
+            self.groups[group.names] = group
             for node_uuid in self.nodes:
                 if node_uuid not in existing_nodes:
-                    self.groups[group.names] = group
                     group.uuids.append(node_uuid)
 
         try: