Dataset.__len__() not returning expected count

[edmondchuc]

I would have expected the following to return a size of 4 for the dataset, but it returns 3.

def test_mem_size():
    data = f"""
            <http://example.com/s> <{RDF.type}> <{SKOS.Concept}> <urn:graph:a> .
            <http://example.com/s> <{SKOS.prefLabel}> "Label" <urn:graph:a> .
            <http://example.com/s> <{SKOS.prefLabel}> "Label" <urn:graph:b> .
            <http://example.com/s> <{SKOS.definition}> "Definition" .
        """
    ds = Dataset()
    ds.parse(data=data, format="nquads")
    assert len(ds) == 4

Not confirmed yet but the dataset appears to be calculating the total number of triples instead of quads. When I remove one of the two skos:prefLabel statements, the count is still 3.

[edmondchuc]

This issue is likely related to #3314.

I haven't been able to fix it, but I noticed a few interesting things. method nquads (meaning 4 parameters) but skos definition has three arguments not four. I tried to add a blank node (BNode) to make the skos definition have four arguments, so it wouldn't be rejected in adding to the DataSet due to having only three arguments.

main...interestingcoder1:rdflib:main