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)

noxfile.py

@@ -86,7 +86,7 @@ def lint(session: nox.Session) -> None:
     )
 
 
-@nox.session
+@nox.session(venv_backend="uv")
 def docs(session: nox.Session) -> None:
     """Build the documentation."""
     output_dir = os.path.join(session.create_tmp(), "output")
@@ -95,7 +95,7 @@ def docs(session: nox.Session) -> None:
     )
     shutil.rmtree(output_dir, ignore_errors=True)
     session.install("-r", "requirements-test.txt")
-    session.install(".")
+    session.install("nox @ .")
     session.cd("docs")
     sphinx_args = ["-b", "html", "-W", "-d", doctrees, ".", html]
 

pyproject.toml

@@ -52,6 +52,9 @@ tox_to_nox = [
   "jinja2",
   "tox<4",
 ]
+uv = [
+  "uv"
+]
 [project.urls]
 bug-tracker = "https://github.com/wntrblm/nox/issues"
 documentation = "https://nox.thea.codes"

tests/test_virtualenv.py

@@ -245,7 +245,7 @@ def test_constructor_defaults(make_one):
     assert venv.location
     assert venv.interpreter is None
     assert venv.reuse_existing is False
-    assert venv.venv_or_virtualenv == "virtualenv"
+    assert venv.venv_prog == "virtualenv"
 
 
 @pytest.mark.skipif(IS_WINDOWS, reason="Not testing multiple interpreters on Windows.")
@@ -442,7 +442,7 @@ def test_create_reuse_stale_virtualenv_environment(make_one):
 
 @enable_staleness_check
 def test_create_reuse_venv_environment(make_one):
-    venv, location = make_one(reuse_existing=True, venv=True)
+    venv, location = make_one(reuse_existing=True, venv="venv")
     venv.create()
 
     # Place a spurious occurrence of "virtualenv" in the pyvenv.cfg.