path and full_path arguments for output renderers, closes #1179

Output renderer render() and can_render() callbacks can now accept
path and full_path arguments - the path to the HTML version of the
page without the .extension, with and without the query string.

Also fixed path_with_format() so it replaces the extension the current
request used instead of falling back to ?_format=, which Datasette no
longer reads. This broke links generated by renderers such as
datasette-export-notebook, and the URLs returned by ?_extra=renderers
on .json pages.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TzcVp1Cq5yCRW81GiN88JX

tests/test_utils.py

@@ -578,6 +578,56 @@ def test_path_with_format_can_override_request_path():
     assert "/foo.json?x=1" == actual
 
 
+@pytest.mark.parametrize(
+    "path,url_vars,expected",
+    [
+        # https://github.com/simonw/datasette/issues/1179
+        ("/db/table.Notebook", {"format": "Notebook"}, "/db/table.json"),
+        ("/db/table.csv?_size=max", {"format": "csv"}, "/db/table.json?_size=max"),
+        ("/db/table", {}, "/db/table.json"),
+    ],
+)
+def test_path_with_format_replaces_current_format(path, url_vars, expected):
+    request = Request.fake(path, url_vars=url_vars)
+    assert utils.path_with_format(request=request, format="json") == expected
+
+
+def test_path_with_format_replaces_current_format_with_path_override():
+    request = Request.fake("/prefix/db/table.csv?x=1", url_vars={"format": "csv"})
+    actual = utils.path_with_format(
+        request=request, path="/db/table.csv", format="json"
+    )
+    assert actual == "/db/table.json?x=1"
+
+
+@pytest.mark.parametrize(
+    "path,url_vars,expected_path,expected_full_path",
+    [
+        ("/db/table", {}, "/db/table", "/db/table"),
+        ("/db/table.json", {"format": "json"}, "/db/table", "/db/table"),
+        (
+            "/db/table.Notebook?_sort=pk",
+            {"format": "Notebook"},
+            "/db/table",
+            "/db/table?_sort=pk",
+        ),
+        (
+            "/prefix/db/-/query.csv?sql=select+1",
+            {"format": "csv"},
+            "/prefix/db/-/query",
+            "/prefix/db/-/query?sql=select+1",
+        ),
+    ],
+)
+def test_path_without_format(path, url_vars, expected_path, expected_full_path):
+    request = Request.fake(path, url_vars=url_vars)
+    assert utils.path_without_format(request) == expected_path
+    assert (
+        utils.path_without_format(request, include_query_string=True)
+        == expected_full_path
+    )
+
+
 @pytest.mark.parametrize(
     "bytes,expected",
     [