Allow skipping uv sync for lock runner via CLI flag

pyproject.toml

@@ -43,7 +43,7 @@ dependencies = [
   "packaging>=24.2",
   "tox>=4.24.1,<5",
   "typing-extensions>=4.12.2; python_version<'3.10'",
-  "uv>=0.5.22,<1",
+  "uv>=0.5.27,<1",
 ]
 urls.Changelog = "https://github.com/tox-dev/tox-uv/releases"
 urls.Documentation = "https://github.com/tox-dev/tox-uv#tox-uv"
@@ -62,14 +62,14 @@ dev = [
 test = [
   "covdefaults>=2.3",
   "devpi-process>=1.0.2",
-  "diff-cover>=9.2.1",
+  "diff-cover>=9.2.2",
   "pytest>=8.3.4",
   "pytest-cov>=6",
   "pytest-mock>=3.14",
 ]
 type = [ "mypy==1.14.1", { include-group = "test" } ]
 lint = [ "pre-commit-uv>=4.1.4" ]
-pkg-meta = [ "check-wheel-contents>=0.6.1", "twine>=6.1", "uv>=0.5.22" ]
+pkg-meta = [ "check-wheel-contents>=0.6.1", "twine>=6.1", "uv>=0.5.27" ]
 
 [tool.hatch]
 build.hooks.vcs.version-file = "src/tox_uv/version.py"

src/tox_uv/_run_lock.py

@@ -60,31 +60,32 @@ def register_config(self) -> None:
 
     def _setup_env(self) -> None:
         super()._setup_env()
-        cmd = [
-            "uv",
-            "sync",
-            "--frozen",
-        ]
-        if self.conf["uv_python_preference"] != "none":
-            cmd.extend(("--python-preference", self.conf["uv_python_preference"]))
-        for extra in cast("set[str]", sorted(self.conf["extras"])):
-            cmd.extend(("--extra", extra))
-        groups = sorted(self.conf["dependency_groups"])
-        if self.conf["no_default_groups"] and not groups:
-            cmd.append("--no-default-groups")
         install_pkg = getattr(self.options, "install_pkg", None)
-        if install_pkg is not None:
-            cmd.append("--no-install-project")
-        if self.options.verbosity > 3:  # noqa: PLR2004
-            cmd.append("-v")
-        for group in groups:
-            cmd.extend(("--group", group))
-        cmd.extend(self.conf["uv_sync_flags"])
-        cmd.extend(("-p", self.env_version_spec()))
-
-        show = self.options.verbosity > 2  # noqa: PLR2004
-        outcome = self.execute(cmd, stdin=StdinSource.OFF, run_id="uv-sync", show=show)
-        outcome.assert_success()
+        if not getattr(self.options, "skip_uv_sync", False):
+            cmd = [
+                "uv",
+                "sync",
+                "--frozen",
+            ]
+            if self.conf["uv_python_preference"] != "none":
+                cmd.extend(("--python-preference", self.conf["uv_python_preference"]))
+            for extra in cast("set[str]", sorted(self.conf["extras"])):
+                cmd.extend(("--extra", extra))
+            groups = sorted(self.conf["dependency_groups"])
+            if self.conf["no_default_groups"] and not groups:
+                cmd.append("--no-default-groups")
+            if install_pkg is not None:
+                cmd.append("--no-install-project")
+            if self.options.verbosity > 3:  # noqa: PLR2004
+                cmd.append("-v")
+            for group in groups:
+                cmd.extend(("--group", group))
+            cmd.extend(self.conf["uv_sync_flags"])
+            cmd.extend(("-p", self.env_version_spec()))
+
+            show = self.options.verbosity > 2  # noqa: PLR2004
+            outcome = self.execute(cmd, stdin=StdinSource.OFF, run_id="uv-sync", show=show)
+            outcome.assert_success()
         if install_pkg is not None:
             path = Path(install_pkg)
             pkg = (WheelPackage if path.suffix == ".whl" else SdistPackage)(path, deps=[])

src/tox_uv/plugin.py

@@ -12,6 +12,7 @@
 from ._run_lock import UvVenvLockRunner
 
 if TYPE_CHECKING:
+    from tox.config.cli.parser import ToxParser
     from tox.tox_env.register import ToxEnvRegister
 
 
@@ -24,6 +25,17 @@ def tox_register_tox_env(register: ToxEnvRegister) -> None:
     register._default_run_env = UvVenvRunner.id()  # noqa: SLF001
 
 
+@impl
+def tox_add_option(parser: ToxParser) -> None:
+    for key in ("run", "exec"):
+        parser.handlers[key][0].add_argument(
+            "--skip-uv-sync",
+            dest="skip_uv_sync",
+            help="skip uv sync (lock mode only)",
+            action="store_true",
+        )
+
+
 def tox_append_version_info() -> str:
     return f"with uv=={version('uv')}"
 

tests/test_tox_uv_lock.py

@@ -454,3 +454,39 @@ def test_uv_sync_uv_python_preference(
         ("py", "commands[0]", ["python", "hello"]),
     ]
     assert calls == expected
+
+
+def test_skip_uv_sync(tox_project: ToxProjectCreator, monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.delenv("UV_PYTHON_PREFERENCE", raising=False)
+    project = tox_project({
+        "tox.toml": """
+    [env_run_base]
+    runner = "uv-venv-lock-runner"
+    commands = [["python", "hello"]]
+    """
+    })
+    execute_calls = project.patch_execute(lambda r: 0 if r.run_id != "venv" else None)
+    result = project.run("run", "--skip-uv-sync")
+    result.assert_success()
+
+    calls = [(i[0][0].conf.name, i[0][3].run_id, i[0][3].cmd) for i in execute_calls.call_args_list]
+    uv = find_uv_bin()
+
+    expected = [
+        (
+            "py",
+            "venv",
+            [
+                uv,
+                "venv",
+                "-p",
+                sys.executable,
+                "--allow-existing",
+                "--python-preference",
+                "system",
+                str(project.path / ".tox" / "py"),
+            ],
+        ),
+        ("py", "commands[0]", ["python", "hello"]),
+    ]
+    assert calls == expected

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 requires =
     tox>=4.24.1
-    tox-uv>=1.20
+    tox-uv>=1.21.1
 env_list =
     fix
     3.13