Remove URL validation from requirement parsing

CHANGELOG.rst

@@ -5,6 +5,7 @@ Changelog
 ~~~~~~~~~~~~
 
 * Enforce that the entire marker string is parsed (:issue:`687`)
+* Requirement parsing no longer automatically validates the URL (:issue:`120`)
 
 23.1 - 2023-04-12
 ~~~~~~~~~~~~~~~~~

docs/requirements.rst

@@ -56,6 +56,13 @@ Usage
     >>> requirements1 == requirements2
     True
 
+.. versionchanged:: 23.2
+
+    When a requirement is specified with a URL, the :class:`Requirement` class
+    used to check the URL and reject values containing invalid scheme and
+    netloc combinations. This is no longer performed since PEP 508 does not
+    specify such rules, and the check incorrectly disallows valid requirement
+    strings from being parsed.
 
 Reference
 ---------

src/packaging/requirements.py

@@ -2,7 +2,6 @@
 # 2.0, and the BSD License. See the LICENSE file in the root of this repository
 # for complete details.
 
-import urllib.parse
 from typing import Any, List, Optional, Set
 
 from ._parser import parse_requirement as _parse_requirement
@@ -37,18 +36,7 @@ def __init__(self, requirement_string: str) -> None:
             raise InvalidRequirement(str(e)) from e
 
         self.name: str = parsed.name
-        if parsed.url:
-            parsed_url = urllib.parse.urlparse(parsed.url)
-            if parsed_url.scheme == "file":
-                if urllib.parse.urlunparse(parsed_url) != parsed.url:
-                    raise InvalidRequirement("Invalid URL given")
-            elif not (parsed_url.scheme and parsed_url.netloc) or (
-                not parsed_url.scheme and not parsed_url.netloc
-            ):
-                raise InvalidRequirement(f"Invalid URL: {parsed.url}")
-            self.url: Optional[str] = parsed.url
-        else:
-            self.url = None
+        self.url: Optional[str] = parsed.url or None
         self.extras: Set[str] = set(parsed.extras if parsed.extras else [])
         self.specifier: SpecifierSet = SpecifierSet(parsed.specifier)
         self.marker: Optional[Marker] = None

tests/test_requirements.py

@@ -78,6 +78,7 @@
         ("git+https://git.example.com/MyProject.git@master", ""),
         ("git+https://git.example.com/MyProject.git@v1.0", ""),
         ("git+https://git.example.com/MyProject.git@refs/pull/123/head", ""),
+        ("gopher:/foo/com", ""),
         (None, "==={ws}arbitrarystring"),
         (None, "({ws}==={ws}arbitrarystring{ws})"),
         (None, "=={ws}1.0"),
@@ -164,6 +165,8 @@ def test_valid_marker(self, marker: str) -> None:
         [
             "file:///absolute/path",
             "file://.",
+            "file:.",
+            "file:/.",
         ],
     )
     def test_file_url(self, url: str) -> None:
@@ -503,25 +506,6 @@ def test_error_invalid_marker_with_invalid_op(self) -> None:
             "                ^"
         )
 
-    @pytest.mark.parametrize(
-        "url",
-        [
-            "gopher:/foo/com",
-            "file:.",
-            "file:/.",
-        ],
-    )
-    def test_error_on_invalid_url(self, url: str) -> None:
-        # GIVEN
-        to_parse = f"name @ {url}"
-
-        # WHEN
-        with pytest.raises(InvalidRequirement) as ctx:
-            Requirement(to_parse)
-
-        # THEN
-        assert "Invalid URL" in ctx.exconly()
-
     def test_error_on_legacy_version_outside_triple_equals(self) -> None:
         # GIVEN
         to_parse = "name==1.0.org1"