feat: add a uv backend

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

nox/sessions.py

@@ -632,7 +632,12 @@ def install(self, *args: str, **kwargs: Any) -> None:
  if "silent" not in kwargs:
  kwargs["silent"] = True
 
- self._run("python", "-m", "pip", "install", *args, external="error", **kwargs)
+ if getattr(venv, "venv_prog", "") == "uv":
+ self._run("uv", "pip", "install", *args, external="error", **kwargs)
+ else:
+ self._run(
+ "python", "-m", "pip", "install", *args, external="error", **kwargs
+ )
 
  def notify(
  self,
@@ -748,11 +753,12 @@ def _create_venv(self) -> None:
  self.func.reuse_venv or self.global_config.reuse_existing_virtualenvs
  )
 
- if backend is None or backend == "virtualenv":
+ if backend is None or backend in {"virtualenv", "venv", "uv"}:
  self.venv = VirtualEnv(
  self.envdir,
  interpreter=self.func.python, # type: ignore[arg-type]
  reuse_existing=reuse_existing,
+ venv=backend or "virtualenv",
  venv_params=self.func.venv_params,
  )
  elif backend in {"conda", "mamba"}:
@@ -763,14 +769,6 @@ def _create_venv(self) -> None:
  venv_params=self.func.venv_params,
  conda_cmd=backend,
  )
- elif backend == "venv":
- self.venv = VirtualEnv(
- self.envdir,
- interpreter=self.func.python, # type: ignore[arg-type]
- reuse_existing=reuse_existing,
- venv=True,
- venv_params=self.func.venv_params,
- )
  else:
  raise ValueError(
  "Expected venv_backend one of ('virtualenv', 'conda', 'mamba',"

nox/virtualenv.py

@@ -312,22 +312,23 @@ class VirtualEnv(ProcessEnv):
  """
 
  is_sandboxed = True
+ allowed_globals = ("uv",)
 
  def __init__(
  self,
  location: str,
  interpreter: str | None = None,
  reuse_existing: bool = False,
  *,
- venv: bool = False,
+ venv: str = "virtualenv",
  venv_params: Any = None,
  ):
  self.location_name = location
  self.location = os.path.abspath(location)
  self.interpreter = interpreter
  self._resolved: None | str | InterpreterNotFound = None
  self.reuse_existing = reuse_existing
- self.venv_or_virtualenv = "venv" if venv else "virtualenv"
+ self.venv_prog = venv
  self.venv_params = venv_params or []
  super().__init__(env={"VIRTUAL_ENV": self.location})
 
@@ -359,7 +360,7 @@ def _check_reused_environment_type(self) -> bool:
  old_env = (
  "virtualenv" if any(pattern.match(line) for line in fp) else "venv"
  )
- return old_env == self.venv_or_virtualenv
+ return old_env == self.venv_prog
 
  def _check_reused_environment_interpreter(self) -> bool:
  """Check if reused environment interpreter is the same."""
@@ -474,18 +475,26 @@ def create(self) -> bool:
 
  return False
 
- if self.venv_or_virtualenv == "virtualenv":
+ if self.venv_prog == "virtualenv":
  cmd = [sys.executable, "-m", "virtualenv", self.location]
  if self.interpreter:
  cmd.extend(["-p", self._resolved_interpreter])
+ elif self.venv_prog == "uv":
+ cmd = [
+ "uv",
+ "virtualenv",
+ "-p",
+ self._resolved_interpreter if self.interpreter else sys.executable,
+ self.location,
+ ]
  else:
  cmd = [self._resolved_interpreter, "-m", "venv", self.location]
  cmd.extend(self.venv_params)
 
  resolved_interpreter_name = os.path.basename(self._resolved_interpreter)
 
  logger.info(
- f"Creating virtual environment ({self.venv_or_virtualenv}) using"
+ f"Creating virtual environment ({self.venv_prog}) using"
  f" {resolved_interpreter_name} in {self.location_name}"
  )
  nox.command.run(cmd, silent=True, log=nox.options.verbose or False)