Merge branch 'master' into hsolbrig/master

# Conflicts:
#	rdflib/namespace/__init__.py
#	rdflib/plugins/sparql/operators.py
#	test/test_namespace.py

1 files changed, 50 insertions, 1 deletions

diff --git a/test/test_diff.py b/test/test_diff.py
index 0fb8d265..e33bd452 100644
--- a/test/test_diff.py
+++ b/test/test_diff.py
@@ -1,10 +1,19 @@
+from typing import Set, Tuple
 import unittest
+from unittest.case import expectedFailure
 import rdflib
 from rdflib.compare import graph_diff
+from rdflib.namespace import RDF, FOAF
+from rdflib import Graph
+from rdflib.term import Node, BNode, Literal
+from .testutils import GraphHelper
 
-"""Test for graph_diff - much more extensive testing 
+"""Test for graph_diff - much more extensive testing
 would certainly be possible"""
 
+_TripleT = Tuple[Node, Node, Node]
+_TripleSetT = Set[_TripleT]
+
 
 class TestDiff(unittest.TestCase):
     """Unicode literals for graph_diff test
@@ -25,6 +34,46 @@ class TestDiff(unittest.TestCase):
 
         diff = graph_diff(g, g)
 
+    @expectedFailure
+    def test_subsets(self) -> None:
+        """
+        This test verifies that `graph_diff` returns the correct values
+        for two graphs, `g0` and `g1` where the triples in `g0` is a
+        subset of the triples in `g1`.
+
+        The expectation is that graph_diff reports that there are no
+        triples only in `g0`, and that there are triples that occur in both
+        `g0` and `g1`, and that there are triples only in `g1`.
+        """
+        g0_ts: _TripleSetT = set()
+        bnode = BNode()
+        g0_ts.update(
+            {
+                (bnode, FOAF.name, Literal("Golan Trevize")),
+                (bnode, RDF.type, FOAF.Person),
+            }
+        )
+        g0 = Graph()
+        g0 += g0_ts
+
+        g1_ts: _TripleSetT = set()
+        bnode = BNode()
+        g1_ts.update(
+            {
+                *g0_ts,
+                (bnode, FOAF.name, Literal("Janov Pelorat")),
+                (bnode, RDF.type, FOAF.Person),
+            }
+        )
+        g1 = Graph()
+        g1 += g1_ts
+
+        result = graph_diff(g0, g1)
+        in_both, in_first, in_second = GraphHelper.triple_sets(result)
+        self.assertFalse(in_first)
+        self.assertTrue(in_second)
+        self.assertTrue(in_both)
+
 
 if __name__ == "__main__":
     unittest.main()