Fix provisioning (#2750)

Author: gaborbernat

src/tox/provision.py

@@ -62,7 +62,7 @@ def provision(state: State) -> int | bool:
         keys=["min_version", "minversion"],
         of_type=Version,
         # do not include local version specifier (because it's not allowed in version spec per PEP-440)
-        default=Version("4.0"),
+        default=None,  # type: ignore # Optional[Version] translates to object
         desc="Define the minimal tox version required to run",
     )
     state.conf.core.add_config(
@@ -72,10 +72,10 @@ def provision(state: State) -> int | bool:
         desc="Name of the virtual environment used to provision a tox.",
     )
 
-    def add_tox_requires_min_version(requires: list[Requirement]) -> list[Requirement]:
+    def add_tox_requires_min_version(reqs: list[Requirement]) -> list[Requirement]:
         min_version: Version = state.conf.core["min_version"]
-        requires.append(Requirement(f"tox >= {min_version}"))
-        return requires
+        reqs.append(Requirement(f"tox{f'>={min_version}' if min_version else ''}"))
+        return reqs
 
     state.conf.core.add_config(
         keys="requires",
@@ -113,8 +113,9 @@ def add_tox_requires_min_version(requires: list[Requirement]) -> list[Requiremen
         msg = f"provisioning explicitly disabled within {sys.executable}, but {miss_msg}"
         if isinstance(no_provision, str):
             msg += f" and wrote to {no_provision}"
+            min_version = str(next(i.specifier for i in requires if i.name == "tox")).split("=")
             requires_dict = {
-                "minversion": str(next(i.specifier for i in requires if i.name == "tox")).split("=")[1],
+                "minversion": min_version[1] if len(min_version) >= 2 else None,
                 "requires": [str(i) for i in requires],
             }
             Path(no_provision).write_text(json.dumps(requires_dict, indent=4))

src/tox/session/env_select.py

@@ -232,11 +232,9 @@ def _finalize_config(self) -> None:
     def _build_run_env(self, name: str) -> RunToxEnv | None:
         if self._provision is not None and self._provision[0] is False and name == self._provision[1]:
             return None
-        env_conf = self._state.conf.get_env(
-            name,
-            package=False,
-            loaders=[self._provision[2]] if self._provision is not None and self._provision[1] == name else None,
-        )
+        env_conf = self._state.conf.get_env(name, package=False)
+        if self._provision is not None and self._provision[1] == name:
+            env_conf.loaders.insert(0, self._provision[2])
         desc = "the tox execute used to evaluate this environment"
         env_conf.add_config(keys="runner", desc=desc, of_type=str, default=self._state.conf.options.default_runner)
         runner = REGISTER.runner(cast(str, env_conf["runner"]))

tests/test_provision.py

@@ -186,4 +186,4 @@ def test_provision_no_recreate_json(tox_project: ToxProjectCreator) -> None:
     assert msg in result.out
     with (project.path / "out.json").open() as file_handler:
         requires = json.load(file_handler)
-    assert requires == {"minversion": "4.0", "requires": ["p", "tox>=4.0"]}
+    assert requires == {"minversion": None, "requires": ["p", "tox"]}