fix: support noxfile being a symlink

nox/tasks.py

@@ -83,13 +83,15 @@ def load_nox_module(global_config: Namespace) -> types.ModuleType | int:
     # Be sure to expand variables
     global_config_noxfile = os.path.expandvars(global_config.noxfile)
 
+    # Make sure we only expand the parent dir just in case the noxfile is a symlink
+    noxfile_parent_dir = os.path.realpath(os.path.dirname(global_config_noxfile))
+
     # Save the absolute path to the Noxfile.
     # This will inoculate it if Nox changes paths because of an implicit
     # or explicit chdir (like the one below).
-    global_config.noxfile = os.path.realpath(global_config_noxfile)
-
-    # Make sure we only expand the parent dir just in case the noxfile is a symlink
-    noxfile_parent_dir = os.path.realpath(os.path.dirname(global_config.noxfile))
+    global_config.noxfile = os.path.join(
+        noxfile_parent_dir, os.path.basename(global_config_noxfile)
+    )
 
     try:
         # Check ``nox.needs_version`` by parsing the AST.

tests/resources/orig_dir/noxfile.py

@@ -0,0 +1,17 @@
+from pathlib import Path
+
+import nox
+
+FILE = Path(__file__).resolve()
+
+
+@nox.session(venv_backend="none", default=False)
+def orig(session: nox.Session) -> None:
+    assert Path("orig_file.txt").exists()
+
+
+@nox.session(venv_backend="none", default=False)
+def sym(session: nox.Session) -> None:
+    assert Path("sym_file.txt").exists()
+
+    assert FILE.parent.joinpath("orig_file.txt").exists()

tests/resources/sym_dir/noxfile.py

@@ -0,0 +1 @@
+../orig_dir/noxfile.py

tests/test_main.py

@@ -16,6 +16,7 @@
 
 import contextlib
 import os
+import subprocess
 import sys
 from importlib import metadata
 from pathlib import Path
@@ -928,3 +929,25 @@ def test_noxfile_options_cant_be_set():
 def test_noxfile_options_cant_be_set_long():
     with pytest.raises(AttributeError, match="i_am_clearly_not_an_option"):
         nox.options.i_am_clearly_not_an_option = True
+
+
+def test_symlink_orig(monkeypatch):
+    monkeypatch.chdir(Path(RESOURCES) / "orig_dir")
+    subprocess.run([sys.executable, "-m", "nox", "-s", "orig"], check=True)
+
+
+def test_symlink_orig_not(monkeypatch):
+    monkeypatch.chdir(Path(RESOURCES) / "orig_dir")
+    res = subprocess.run([sys.executable, "-m", "nox", "-s", "sym"], check=False)
+    assert res.returncode == 1
+
+
+def test_symlink_sym(monkeypatch):
+    monkeypatch.chdir(Path(RESOURCES) / "sym_dir")
+    subprocess.run([sys.executable, "-m", "nox", "-s", "sym"], check=True)
+
+
+def test_symlink_sym_not(monkeypatch):
+    monkeypatch.chdir(Path(RESOURCES) / "sym_dir")
+    res = subprocess.run([sys.executable, "-m", "nox", "-s", "orig"], check=False)
+    assert res.returncode == 1