fix: Dataset.parse now returns Self (#3263)

* fix: Dataset.parse now returns Self

* chore: remove test that's not relevant for this PR

Author: edmondchuc

rdflib/graph.py

@@ -2346,8 +2346,7 @@ def parse(
 
         context = self.default_context
         context.parse(source, publicID=publicID, format=format, **args)
-        # TODO: FIXME: This should not return context, but self.
-        return context
+        return self
 
     def __reduce__(self) -> Tuple[Type[Graph], Tuple[Store, _ContextIdentifierType]]:
         return ConjunctiveGraph, (self.store, self.identifier)
@@ -2615,11 +2614,10 @@ def parse(
         (i.e. :attr:`.Dataset.default_context`).
         """
 
-        c = ConjunctiveGraph.parse(
+        ConjunctiveGraph.parse(
             self, source, publicID, format, location, file, data, **args
         )
-        self.graph(c)
-        return c
+        return self
 
     def add_graph(
         self, g: Optional[Union[_ContextIdentifierType, _ContextType, str]]

rdflib/plugins/parsers/nquads.py

@@ -7,7 +7,7 @@
 >>> g = ConjunctiveGraph()
 >>> data = open("test/data/nquads.rdflib/example.nquads", "rb")
 >>> g.parse(data, format="nquads") # doctest:+ELLIPSIS
-<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
+<Graph identifier=... (<class 'rdflib.graph.ConjunctiveGraph'>)>
 >>> assert len(g.store) == 449
 >>> # There should be 16 separate contexts
 >>> assert len([x for x in g.store.contexts()]) == 16

test/test_dataset/test_dataset_add.py

@@ -1,4 +1,5 @@
 from rdflib import RDF, RDFS, Dataset, Graph, URIRef
+from test.data import TEST_DATA_DIR
 
 
 def test_behaviour_where_graph_is_created_via_dataset():
@@ -86,3 +87,15 @@ def test_adding_appends_to_dataset_graph():
     graph = ds.add_graph(another_graph)
     assert len(graph) == 3
     assert len(ds) == 3
+
+
+def test_dataset_parse_return_value():
+    """
+    Test that the return value of ds.parse has the same reference as ds.
+    """
+    ds = Dataset()
+    return_value = ds.parse(
+        source=TEST_DATA_DIR / "nquads.rdflib/example.nquads", format="nquads"
+    )
+    assert len(ds)
+    assert return_value is ds