Add tests demonstrating forward-slash behaviors in Turtle, JSON-LD, a…

…nd SPARQL

Some correction is needed in the SPARQL engine to get these tests to
pass.

References:
* RDFLib#1871

Signed-off-by: Alex Nelson <alexander.nelson@nist.gov>

test/test_sparql/test_forward_slash_escapes.py

@@ -0,0 +1,259 @@
+#!/usr/bin/env python3
+
+# This software was developed at the National Institute of Standards
+# and Technology by employees of the Federal Government in the course
+# of their official duties. Pursuant to title 17 Section 105 of the
+# United States Code this software is not subject to copyright
+# protection and is in the public domain. NIST assumes no
+# responsibility whatsoever for its use by other parties, and makes
+# no guarantees, expressed or implied, about its quality,
+# reliability, or any other characteristic.
+#
+# We would appreciate acknowledgement if the software is used.
+
+"""
+This test-set demonstrates usage of identifier prefixing and the
+forward-slash character in Turtle, JSON-LD, and SPARQL.  The motivating
+use case originated with attempts to interact with IANA Media Types as
+prefixed concepts, e.g. "application/json" somehow being
+"mime:application/json".
+"""
+
+from typing import Set, Tuple
+
+import pytest
+from rdflib import Graph
+from rdflib.term import Node
+from rdflib.plugins.sparql.processor import prepareQuery
+
+# Note that the data and query strings are Python raw strings, so
+# backslashes won't be escape characters to Python.
+# The "*_expanded" variables eschew prefixing.
+
+# Spell a class name without prefixing.
+turtle_data_expanded = r"""
+@prefix kb: <http://example.org/kb/> .
+@prefix owl: <http://www.w3.org/2002/07/owl#> .
+
+<http://example.org/ontology/core/MyClassA> a owl:Class .
+
+kb:individual-a a <http://example.org/ontology/core/MyClassA> .
+"""
+
+# Spell a class name with prefixing, but have the prefixing NOT include
+# one of the forward-slashed path components.
+# The forward slash must be escaped, according to Turtle grammar
+# production rules grammar rules including and between PN_LOCAL and
+# PN_LOCAL_ESC.
+# https://www.w3.org/TR/turtle/#sec-grammar-grammar
+turtle_data_prefixed = r"""
+@prefix ex: <http://example.org/ontology/> .
+@prefix kb: <http://example.org/kb/> .
+@prefix owl: <http://www.w3.org/2002/07/owl#> .
+
+ex:core\/MyClassB a owl:Class .
+
+kb:individual-b a ex:core\/MyClassB .
+"""
+
+# This data is an equivalant graph with turtle_data_expanded.
+jsonld_data_expanded = r"""
+{
+    "@context": {
+        "kb": "http://example.org/kb/",
+        "owl": "http://www.w3.org/2002/07/owl#"
+    },
+    "@graph": {
+        "@id": "kb:individual-a",
+        "@type": {
+            "@id": "http://example.org/ontology/core/MyClassA",
+            "@type": "owl:Class"
+        }
+    }
+}
+"""
+
+# This data is an equivalant graph with turtle_data_prefixed.
+# The JSON-LD spec does not provide a grammar production rule set in
+# EBNF.  However, the section on compact IRIs indicates that an IRI can
+# be prefixed at any point that would not result in a suffix starting
+# with "//".  Hence, an unpaired forward slash, as a legal character of
+# an IRI, can appear in the suffix component of a compact IRI.
+# https://json-ld.org/spec/latest/json-ld/#compact-iris
+jsonld_data_prefixed = r"""
+{
+    "@context": {
+        "ex": "http://example.org/ontology/",
+        "kb": "http://example.org/kb/",
+        "owl": "http://www.w3.org/2002/07/owl#"
+    },
+    "@graph": {
+        "@id": "kb:individual-b",
+        "@type": {
+            "@id": "ex:core/MyClassB",
+            "@type": "owl:Class"
+        }
+    }
+}
+"""
+
+query_string_expanded = r"""
+SELECT ?nIndividual
+WHERE {
+  ?nIndividual a <http://example.org/ontology/core/MyClassB> .
+}"""
+
+# NOTE: This is expected to fail.  The SPARQL grammar production rules
+# for prefixed IRIs, especially at production rule PN_LOCAL, have no way
+# to reach the forward-slash or backslash characters.
+# https://www.w3.org/TR/rdf-sparql-query/#grammar
+query_string_prefixed = r"""
+PREFIX ex: <http://example.org/ontology/>
+SELECT ?nIndividual
+WHERE {
+  # NOTE: Syntax is incorrect - forward slash cannot be included in
+  # local component of name.
+  ?nIndividual a ex:core\/MyClassB .
+}"""
+
+
+def _test_parse_matches(turtle_data: str, jsonld_data: str) -> None:
+    """
+    Confirm that the two concrete syntaxes parse to the same set of
+    triples.
+    """
+    g_turtle = Graph()
+    g_jsonld = Graph()
+
+    g_turtle.parse(data=turtle_data_expanded, format="turtle")
+    g_jsonld.parse(data=jsonld_data_expanded, format="json-ld")
+
+    triples_turtle: Set[Tuple[Node, Node, Node]] = {
+        x for x in g_turtle.triples((None, None, None))
+    }
+    triples_jsonld: Set[Tuple[Node, Node, Node]] = {
+        x for x in g_jsonld.triples((None, None, None))
+    }
+
+    assert triples_turtle == triples_jsonld
+
+
+def test_parse_matches_expanded() -> None:
+    _test_parse_matches(turtle_data_expanded, jsonld_data_expanded)
+
+
+def test_parse_matches_prefixed() -> None:
+    _test_parse_matches(turtle_data_prefixed, jsonld_data_prefixed)
+
+
+def _test_escapes_to_iri(graph: Graph) -> None:
+    """
+    Confirm all triple-subjects within the two data graphs are found.
+    """
+    expected: Set[str] = {
+        "http://example.org/kb/individual-a",
+        "http://example.org/kb/individual-b",
+        "http://example.org/ontology/core/MyClassA",
+        "http://example.org/ontology/core/MyClassB",
+    }
+    computed: Set[str] = set()
+
+    for triple in graph.triples((None, None, None)):
+        computed.add(str(triple[0]))
+
+    assert expected == computed
+
+
+def test_escapes_to_iri_turtle() -> None:
+    graph = Graph()
+    graph.parse(data=turtle_data_expanded, format="turtle")
+    graph.parse(data=turtle_data_prefixed, format="turtle")
+    _test_escapes_to_iri(graph)
+
+
+def test_escapes_to_iri_jsonld() -> None:
+    graph = Graph()
+    graph.parse(data=jsonld_data_expanded, format="json-ld")
+    graph.parse(data=jsonld_data_prefixed, format="json-ld")
+    _test_escapes_to_iri(graph)
+
+
+def _test_query_prepares(query_string: str) -> None:
+    """
+    Confirm parse behavior of SPARQL engine when a concept would be
+    prefixed at a point that leaves a forward-slash character in the
+    suffix.
+    """
+    nsdict = {
+        "ex": "http://example.org/ontology/",
+        "kb": "http://example.org/kb/",
+        "owl": "http://www.w3.org/2002/07/owl#",
+    }
+    query_object = prepareQuery(query_string, initNs=nsdict)
+
+
+def test_query_prepares_expanded() -> None:
+    _test_query_prepares(query_string_expanded)
+
+
+@pytest.mark.xfail(reason="Syntax error demonstrated in SPARQL query.", strict=True)
+def test_query_prepares_prefixed() -> None:
+    _test_query_prepares(query_string_prefixed)
+
+
+def _test_escapes_and_query(
+    graph: Graph, query_string: str, expected_query_ran: bool
+) -> None:
+    """
+    Confirm search-results behavior of SPARQL engine when a concept
+    would be prefixed at a point that leaves a forward-slash character
+    in the suffix.
+
+    Note that _test_query_prepares also exercises the expected parse
+    failure.  This parameterized test is more for demonstrating that
+    searching can work without prefixes.
+    """
+    expected: Set[str] = {
+        "http://example.org/kb/individual-b",
+    }
+    computed: Set[str] = set()
+
+    query_ran: bool = False
+    try:
+        for result in graph.query(query_string):
+            query_ran = True
+            computed.add(str(result[0]))
+    except:
+        pass
+
+    assert expected_query_ran == query_ran
+
+    assert expected == computed
+
+
+def test_escapes_and_query_turtle_expanded() -> None:
+    graph = Graph()
+    graph.parse(data=turtle_data_expanded, format="turtle")
+    graph.parse(data=turtle_data_prefixed, format="turtle")
+    _test_escapes_and_query(graph, query_string_expanded, True)
+
+
+def test_escapes_and_query_turtle_prefixed() -> None:
+    graph = Graph()
+    graph.parse(data=turtle_data_expanded, format="turtle")
+    graph.parse(data=turtle_data_prefixed, format="turtle")
+    _test_escapes_and_query(graph, query_string_prefixed, False)
+
+
+def test_escapes_and_query_jsonld_expanded() -> None:
+    graph = Graph()
+    graph.parse(data=jsonld_data_expanded, format="json-ld")
+    graph.parse(data=jsonld_data_prefixed, format="json-ld")
+    _test_escapes_and_query(graph, query_string_expanded, True)
+
+
+def test_escapes_and_query_jsonld_prefixed() -> None:
+    graph = Graph()
+    graph.parse(data=jsonld_data_expanded, format="json-ld")
+    graph.parse(data=jsonld_data_prefixed, format="json-ld")
+    _test_escapes_and_query(graph, query_string_prefixed, False)