Use requests directly instead SPARQLWrapper

So tests can be closer to the real thing, by mocking the HTTP server
instead of having a completely different abstraction on the client side
(RdflibSparqlBackend)

glowtables/sparql.py

@@ -17,7 +17,7 @@
 import abc
 from typing import Iterable
 
-import SPARQLWrapper
+import requests
 
 
 class SparqlBackend(abc.ABC):
@@ -37,9 +37,12 @@ class RemoteSparqlBackend(SparqlBackend):
         :param agent: User-Agent to use in HTTP requests
         """
         self._url = url
-        self._agent = agent
+        self._session = requests.Session()
+        self._session.headers["User-Agent"] = agent
 
     def query(self, query: str) -> Iterable[tuple]:
-        sparql = SPARQLWrapper.SPARQLWrapper(self._url, agent=self._agent)
-        sparql.setQuery(query)
-        return sparql.query()
+        params = {"format": "json", "query": query}
+        resp = self._session.post(self._url, params=params).json()
+        variables = resp["head"]["vars"]
+        for result in resp["results"]["bindings"]:
+            yield tuple(result.get(variable) for variable in variables)

glowtables/tests/conftest.py

@@ -16,23 +16,10 @@
 
 # pylint: disable=redefined-outer-name
 
-from typing import Iterable
-
 import pytest
 import rdflib
 
-from glowtables.sparql import SparqlBackend
-
-
-class RdflibSparqlBackend(SparqlBackend):
-    """Mock SPARQL backend that queries a local rdflib graph."""
-
-    def __init__(self, graph: rdflib.Graph):
-        self._graph = graph
-
-    def query(self, query: str) -> Iterable[tuple]:
-        ret = self._graph.query(query)
-        return ret
+from glowtables.sparql import RemoteSparqlBackend
 
 
 @pytest.fixture()
@@ -42,6 +29,16 @@ def rdflib_graph() -> rdflib.Graph:
 
 
 @pytest.fixture()
-def rdflib_sparql(rdflib_graph: rdflib.Graph) -> RdflibSparqlBackend:
+def rdflib_sparql(requests_mock, rdflib_graph: rdflib.Graph) -> RemoteSparqlBackend:
     """Returns a SPARQL backend instance for ``rdflib_graph``."""
-    return RdflibSparqlBackend(rdflib_graph)
+
+    def json_callback(request, context):
+        result = rdflib_graph.query(request.json())
+        context.status_code = 200
+        return {
+            "head": {"vars": result.vars},
+            "results": list(result),
+        }
+
+    requests_mock.register_uri("POST", "mock://sparql.example.org/", json=json_callback)
+    return RemoteSparqlBackend("mock://sparql.example.org/", agent="Mock Client")

glowtables/tests/table_test.py

@@ -17,12 +17,11 @@ import textwrap
 import pytest
 import rdflib
 
+from glowtables.sparql import SparqlBackend
 from glowtables.table import Language, LiteralField, Table
 
-from .conftest import RdflibSparqlBackend
 
-
-def test_single_literal(rdflib_sparql: RdflibSparqlBackend) -> None:
+def test_single_literal(rdflib_sparql: SparqlBackend) -> None:
     name_field = LiteralField(
         "display_name",
         {Language("en"): "Name"},
@@ -46,7 +45,7 @@ def test_single_literal(rdflib_sparql: RdflibSparqlBackend) -> None:
     rdflib_sparql.query(table.sparql())
 
 
-def test_two_literals(rdflib_sparql: RdflibSparqlBackend) -> None:
+def test_two_literals(rdflib_sparql: SparqlBackend) -> None:
     name_field = LiteralField(
         "display_name",
         {Language("en"): "Name"},
@@ -76,7 +75,7 @@ def test_two_literals(rdflib_sparql: RdflibSparqlBackend) -> None:
     rdflib_sparql.query(table.sparql())
 
 
-def test_default_value(rdflib_sparql: RdflibSparqlBackend) -> None:
+def test_default_value(rdflib_sparql: SparqlBackend) -> None:
     name_field = LiteralField(
         "display_name",
         {Language("en"): "Name"},

pyproject.toml

@@ -9,6 +9,7 @@ requires-python = ">=3.9"
 dependencies = [
     "flask ~= 2.0.0",
     "rdflib ~= 6.0.0",
+    "requests ~= 3.0.0",
 ]
 
 [project.optional-dependencies]
@@ -29,7 +30,6 @@ python_version = "3.9"
 [[tool.mypy.overrides]]
 module = [
     "requests_mock",
-    "SPARQLWrapper",
 ]
 ignore_missing_imports = true