Fix Graph.parse URL handling on windows

Using `pathlib.Path("http://example.com/").exists()` on windows causes an exception as a URL
is not a valid path, while `os.path.exists("http://example.com/")` just
returns false.

This patch reverts _create_input_source_from_location to using
`os.path.exists()` instead of pathlib.Path to make it possible to parse
graphs from http URLs on windows.

rdflib/parser.py

@@ -307,10 +307,13 @@ def create_input_source(
 
 
 def _create_input_source_from_location(file, format, input_source, location):
-    # Fix for Windows problem https://github.com/RDFLib/rdflib/issues/145
-    path = pathlib.Path(location)
-    if path.exists():
-        location = path.absolute().as_uri()
+    # Fix for Windows problem https://github.com/RDFLib/rdflib/issues/145 and
+    # https://github.com/RDFLib/rdflib/issues/1430
+    # NOTE: using pathlib.Path.exists on a URL fails on windows as it is not a
+    # valid path. However os.path.exists() returns false for a URL on windows
+    # which is why it is being used instead.
+    if os.path.exists(location):
+        location = pathlib.Path(location).absolute().as_uri()
 
     base = pathlib.Path.cwd().as_uri()
 

test/test_graph.py

@@ -9,9 +9,14 @@
 from rdflib import URIRef, Graph, plugin
 from rdflib.exceptions import ParserError
 from rdflib.plugin import PluginException
+from rdflib.namespace import Namespace
 
 from nose.exc import SkipTest
 
+from pathlib import Path
+
+from test.testutils import GraphHelper
+
 
 class GraphTestCase(unittest.TestCase):
     store = "default"
@@ -326,6 +331,20 @@ def testGuessFormatForParse(self):
             # this endpoint is currently not available, ignore this test.
             pass
 
+    def test_parse_file_uri(self):
+        EG = Namespace("http://example.org/#")
+        g = Graph()
+        g.parse(Path("./test/nt/simple-04.nt").absolute().as_uri())
+        triple_set = GraphHelper.triple_set(g)
+        self.assertEqual(
+            triple_set,
+            {
+                (EG["Subject"], EG["predicate"], EG["ObjectP"]),
+                (EG["Subject"], EG["predicate"], EG["ObjectQ"]),
+                (EG["Subject"], EG["predicate"], EG["ObjectR"]),
+            },
+        )
+
     def testTransitive(self):
         person = URIRef("ex:person")
         dad = URIRef("ex:dad")

test/test_graph_http.py

@@ -63,7 +63,7 @@ def log_message(self, *args):
 
 
 class TestGraphHTTP(unittest.TestCase):
-    def content_negotiation(self) -> None:
+    def test_content_negotiation(self) -> None:
         EG = Namespace("http://example.org/")
         expected = Graph()
         expected.add((EG["a"], EG["b"], EG["c"]))
@@ -77,6 +77,29 @@ def content_negotiation(self) -> None:
                 graph.parse(url, format=format)
                 self.assertEqual(expected_triples, GraphHelper.triple_set(graph))
 
+    def test_source(self) -> None:
+        EG = Namespace("http://example.org/")
+        expected = Graph()
+        expected.add((EG["a"], EG["b"], EG["c"]))
+        expected_triples = GraphHelper.triple_set(expected)
+
+        httpmock = SimpleHTTPMock()
+        with ctx_http_server(httpmock.Handler) as server:
+            (host, port) = server.server_address
+            url = f"http://{host}:{port}/"
+
+            httpmock.do_get_responses.append(
+                MockHTTPResponse(
+                    200,
+                    "OK",
+                    f"<{EG['a']}> <{EG['b']}> <{EG['c']}>.".encode(),
+                    {"Content-Type": ["text/turtle"]},
+                )
+            )
+            graph = Graph()
+            graph.parse(source=url)
+            self.assertEqual(expected_triples, GraphHelper.triple_set(graph))
+
     def test_3xx(self) -> None:
         EG = Namespace("http://example.com/")
         expected = Graph()