Split up Windows tests relying on urlunparse behaviour

There was a behavioural change to `urllib.parse.urlunparse`[1] that
affects some of our tests on Windows. With the understanding that the
new behaviour is indeed desired, split up some tests relying on this
behaviour depending on the version of Python.

This currently affects only 3.12 and 3.13 but there are other backports
for that change in review upstream, so we'll likely need to update this
in the future.

[1] python/cpython#113563

tests/lib/__init__.py

@@ -1375,3 +1375,24 @@ def __call__(
 
 
 CertFactory = Callable[[], str]
+
+# versions containing fix/backport from https://github.com/python/cpython/pull/113563
+# which changed the behavior of `urllib.parse.urlun{parse,split}`
+has_new_urlun_behavior = (
+    # https://github.com/python/cpython/commit/387ff96e95b9f8a8cc7e646523ba3175b1350669
+    (sys.version_info[:2] == (3, 12) and sys.version_info >= (3, 12, 4))
+    or
+    # https://github.com/python/cpython/commit/872000606271c52d989e53fe4cc9904343d81855
+    (sys.version_info[:2] == (3, 13) and sys.version_info >= (3, 13, 0, "beta", 2))
+)
+
+# the above change seems to only impact tests on Windows, so just add skips for that
+skip_needs_new_urlun_behavior_win = pytest.mark.skipif(
+    sys.platform != "win32" or not has_new_urlun_behavior,
+    reason="testing windows behavior for newer CPython",
+)
+
+skip_needs_old_urlun_behavior_win = pytest.mark.skipif(
+    sys.platform != "win32" or has_new_urlun_behavior,
+    reason="testing windows behavior for older CPython",
+)

tests/unit/test_collector.py

@@ -35,7 +35,12 @@
     _ensure_quoted_url,
 )
 from pip._internal.network.session import PipSession
-from tests.lib import TestData, make_test_link_collector
+from tests.lib import (
+    TestData,
+    make_test_link_collector,
+    skip_needs_new_urlun_behavior_win,
+    skip_needs_old_urlun_behavior_win,
+)
 
 ACCEPT = ", ".join(
     [
@@ -383,10 +388,12 @@ def test_clean_url_path_with_local_path(path: str, expected: str) -> None:
         pytest.param(
             "file:///T:/path/with spaces/",
             "file:///T:/path/with%20spaces",
-            marks=pytest.mark.skipif(
-                "sys.platform != 'win32' or "
-                "sys.version_info == (3, 13, 0, 'beta', 2)"
-            ),
+            marks=skip_needs_old_urlun_behavior_win,
+        ),
+        pytest.param(
+            "file:///T:/path/with spaces/",
+            "file://///T:/path/with%20spaces",
+            marks=skip_needs_new_urlun_behavior_win,
         ),
         # URL with Windows drive letter, running on non-windows
         # platform. The `:` after the drive should be quoted.
@@ -399,10 +406,12 @@ def test_clean_url_path_with_local_path(path: str, expected: str) -> None:
         pytest.param(
             "git+file:///T:/with space/repo.git@1.0#egg=my-package-1.0",
             "git+file:///T:/with%20space/repo.git@1.0#egg=my-package-1.0",
-            marks=pytest.mark.skipif(
-                "sys.platform != 'win32' or "
-                "sys.version_info == (3, 13, 0, 'beta', 2)"
-            ),
+            marks=skip_needs_old_urlun_behavior_win,
+        ),
+        pytest.param(
+            "git+file:///T:/with space/repo.git@1.0#egg=my-package-1.0",
+            "git+file://///T:/with%20space/repo.git@1.0#egg=my-package-1.0",
+            marks=skip_needs_new_urlun_behavior_win,
         ),
         # Test a VCS URL with a Windows drive letter and revision,
         # running on non-windows platform.

tests/unit/test_urls.py

@@ -5,6 +5,10 @@
 import pytest
 
 from pip._internal.utils.urls import path_to_url, url_to_path
+from tests.lib import (
+    skip_needs_new_urlun_behavior_win,
+    skip_needs_old_urlun_behavior_win,
+)
 
 
 @pytest.mark.skipif("sys.platform == 'win32'")
@@ -23,12 +27,14 @@ def test_path_to_url_unix() -> None:
         pytest.param(
             r"\\unc\as\path",
             "file://unc/as/path",
-            marks=pytest.mark.skipif(
-                "sys.platform != 'win32' or "
-                "sys.version_info == (3, 13, 0, 'beta', 2)"
-            ),
+            marks=skip_needs_old_urlun_behavior_win,
             id="unc-path",
         ),
+        pytest.param(
+            r"\\unc\as\path",
+            "file:////unc/as/path",
+            marks=skip_needs_new_urlun_behavior_win,
+        ),
     ],
 )
 def test_path_to_url_win(path: str, url: str) -> None: