fix: look for uv next to python if it's not on PATH

.pre-commit-config.yaml

@@ -40,6 +40,7 @@ repos:
           - jinja2
           - packaging
           - importlib_metadata
+          - uv
 
   - repo: https://github.com/codespell-project/codespell
     rev: v2.2.6

nox/virtualenv.py

@@ -39,6 +39,23 @@
 _SYSTEM = platform.system()
 
 
+def find_uv() -> str | None:
+    uv = shutil.which("uv")
+    if uv is not None:
+        return uv
+
+    # Look for uv in Nox's environment as well, to handle `pipx install nox[uv]`.
+    with contextlib.suppress(ImportError, FileNotFoundError):
+        from uv import find_uv_bin
+
+        return find_uv_bin()
+
+    return None
+
+
+UV = find_uv()
+
+
 class InterpreterNotFound(OSError):
     def __init__(self, interpreter: str) -> None:
         super().__init__(f"Python interpreter {interpreter} not found")
@@ -524,7 +541,7 @@ def create(self) -> bool:
                 cmd.extend(["-p", self._resolved_interpreter])
         elif self.venv_backend == "uv":
             cmd = [
-                "uv",
+                UV or "uv",
                 "venv",
                 "-p",
                 self._resolved_interpreter if self.interpreter else sys.executable,
@@ -560,5 +577,5 @@ def create(self) -> bool:
 OPTIONAL_VENVS = {
     "conda": shutil.which("conda") is not None,
     "mamba": shutil.which("mamba") is not None,
-    "uv": shutil.which("uv") is not None,
+    "uv": UV is not None,
 }

tests/test_virtualenv.py

@@ -19,6 +19,7 @@
 import shutil
 import subprocess
 import sys
+import types
 from textwrap import dedent
 from typing import NamedTuple
 from unittest import mock
@@ -538,6 +539,28 @@ def test_create_reuse_uv_environment(make_one):
     assert reused
 
 
+UV_IN_PIPX_VENV = "/home/user/.local/pipx/venvs/nox/bin/uv"
+
+
+@pytest.mark.parametrize(
+    ["which_result", "find_uv_bin_result", "expected"],
+    [
+        ("/usr/bin/uv", UV_IN_PIPX_VENV, "/usr/bin/uv"),
+        ("/usr/bin/uv", None, "/usr/bin/uv"),
+        (None, UV_IN_PIPX_VENV, UV_IN_PIPX_VENV),
+        (None, None, None),
+    ],
+)
+def test_find_uv_path(monkeypatch, which_result, find_uv_bin_result, expected):
+    monkeypatch.setattr(shutil, "which", lambda _: which_result)
+    monkeypatch.setitem(
+        sys.modules,
+        "uv",
+        types.SimpleNamespace(find_uv_bin=lambda: find_uv_bin_result),
+    )
+    assert nox.virtualenv.find_uv() == expected
+
+
 def test_create_reuse_venv_environment(make_one, monkeypatch):
     # Making the reuse requirement more strict
     monkeypatch.setenv("NOX_ENABLE_STALENESS_CHECK", "1")