Provision: ignore other test environments (#2865)

Fix https://github.com/tox-dev/tox/issues/2862

6 files changed, 72 insertions, 7 deletions

diff --git a/docs/changelog/2862.bugfix.rst b/docs/changelog/2862.bugfix.rst
new file mode 100644
index 00000000..c52228ff
--- /dev/null
+++ b/docs/changelog/2862.bugfix.rst
@@ -0,0 +1,4 @@
+The provision environment (``.tox``) will never inherit from ``testenv``.
+During provisioning, other test environments are not processed, allowing the
+use of keys and values that may be registered by later tox version or
+provisioned plugins - by :user:`masenf`.
diff --git a/docs/upgrading.rst b/docs/upgrading.rst
index 90b2c550..b44fae87 100644
--- a/docs/upgrading.rst
+++ b/docs/upgrading.rst
@@ -317,3 +317,10 @@ version is above the version this feature was added to it, for example for setup
     [testenv:dev]
     deps = setuptools>=64
     package = editable
+
+Provisioning environment
+------------------------
+
+The provisioning environment is triggered when ``minversion`` or ``requires`` are specified and the current environment
+does not satisfy the requirement. In tox 4, the provisioning environment (``.tox`` by default) must be explicitly
+configured and will not inherit values from ``[testenv]`` section.
diff --git a/src/tox/provision.py b/src/tox/provision.py
index 34b56d07..9b1aeba5 100644
--- a/src/tox/provision.py
+++ b/src/tox/provision.py
@@ -97,7 +97,8 @@ def provision(state: State) -> int | bool:
         recreate=state.conf.options.recreate and not state.conf.options.no_recreate_provision,
     )
     provision_tox_env: str = state.conf.core["provision_tox_env"]
-    state.envs._mark_provision(bool(missing), provision_tox_env, loader)
+    state.conf.memory_seed_loaders[provision_tox_env].append(loader)
+    state.envs._mark_provision(bool(missing), provision_tox_env)
 
     from tox.plugin.manager import MANAGER
 
diff --git a/src/tox/session/env_select.py b/src/tox/session/env_select.py
index f926beda..52f11953 100644
--- a/src/tox/session/env_select.py
+++ b/src/tox/session/env_select.py
@@ -13,7 +13,6 @@ from tox.tox_env.api import ToxEnvCreateArgs
 from tox.tox_env.register import REGISTER
 from tox.tox_env.runner import RunToxEnv
 
-from ..config.loader.memory import MemoryLoader
 from ..config.types import EnvList
 from ..report import HandledError
 from ..tox_env.errors import Skip
@@ -134,7 +133,7 @@ class EnvSelector:
         self._manager = MANAGER
         self._log_handler = self._state._options.log_handler
         self._journal = self._state._journal
-        self._provision: None | tuple[bool, str, MemoryLoader] = None
+        self._provision: None | tuple[bool, str] = None
 
         self._state.conf.core.add_config("labels", Dict[str, EnvList], {}, "core labels")
         tox_env_filter_regex = getattr(state.conf.options, "skip_env", "").strip()
@@ -242,10 +241,12 @@ class EnvSelector:
 
     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]:
+            # ignore provision env unless this is a provision run
+            return None
+        if self._provision is not None and self._provision[0] and name != self._provision[1]:
+            # ignore other envs when this is a provision run
             return 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"]))
@@ -367,8 +368,8 @@ class EnvSelector:
         if invalid:
             raise HandledError(f"cannot run packaging environment(s) {','.join(invalid)}")
 
-    def _mark_provision(self, on: bool, provision_tox_env: str, loader: MemoryLoader) -> None:
-        self._provision = on, provision_tox_env, loader
+    def _mark_provision(self, on: bool, provision_tox_env: str) -> None:
+        self._provision = on, provision_tox_env
 
 
 __all__ = [
diff --git a/tests/demo_pkg_inline/build.py b/tests/demo_pkg_inline/build.py
index 35e22f03..47df3a3d 100644
--- a/tests/demo_pkg_inline/build.py
+++ b/tests/demo_pkg_inline/build.py
@@ -14,11 +14,38 @@ pkg_name = name.replace("_", "-")
 version = "1.0.0"
 dist_info = "{}-{}.dist-info".format(name, version)
 logic = "{}/__init__.py".format(name)
+plugin = "{}/example_plugin.py".format(name)
+entry_points = "{}/entry_points.txt".format(dist_info)
 metadata = "{}/METADATA".format(dist_info)
 wheel = "{}/WHEEL".format(dist_info)
 record = "{}/RECORD".format(dist_info)
 content = {
     logic: "def do():\n    print('greetings from {}')".format(name),
+    plugin: dedent(
+        """
+        try:
+            from tox.plugin import impl
+            from tox.tox_env.python.virtual_env.runner import VirtualEnvRunner
+            from tox.tox_env.register import ToxEnvRegister
+        except ImportError:
+            pass
+        else:
+            class ExampleVirtualEnvRunner(VirtualEnvRunner):
+                @staticmethod
+                def id() -> str:
+                    return "example"
+            @impl
+            def tox_register_tox_env(register: ToxEnvRegister) -> None:
+                register.add_run_env(ExampleVirtualEnvRunner)
+    """,
+    ),
+    entry_points: dedent(
+        """
+        [tox]
+        example = {}.example_plugin""".format(
+            name,
+        ),
+    ),
     metadata: """
         Metadata-Version: 2.1
         Name: {}
diff --git a/tests/test_provision.py b/tests/test_provision.py
index c7a7fac2..91d7689d 100644
--- a/tests/test_provision.py
+++ b/tests/test_provision.py
@@ -187,3 +187,28 @@ def test_provision_no_recreate_json(tox_project: ToxProjectCreator) -> None:
     with (project.path / "out.json").open() as file_handler:
         requires = json.load(file_handler)
     assert requires == {"minversion": None, "requires": ["p", "tox"]}
+
+
+@pytest.mark.integration()
+@pytest.mark.usefixtures("_pypi_index_self")
+@pytest.mark.parametrize("plugin_testenv", ["testenv", "testenv:a"])
+def test_provision_plugin_runner(tox_project: ToxProjectCreator, tmp_path: Path, plugin_testenv: str) -> None:
+    """Ensure that testenv runner doesn't affect the provision env."""
+    log = tmp_path / "out.log"
+    proj = tox_project({"tox.ini": f"[tox]\nrequires=demo-pkg-inline\n[{plugin_testenv}]\nrunner=example"})
+    result_first = proj.run("r", "-e", "py", "--result-json", str(log))
+    result_first.assert_success()
+    prov_msg = (
+        f"ROOT: will run in automatically provisioned tox, host {sys.executable} is missing"
+        f" [requires (has)]: demo-pkg-inline"
+    )
+    assert prov_msg in result_first.out
+
+
+@pytest.mark.integration()
+def test_provision_plugin_runner_in_provision(tox_project: ToxProjectCreator, tmp_path: Path) -> None:
+    """Ensure that provision environment can be explicitly configured."""
+    log = tmp_path / "out.log"
+    proj = tox_project({"tox.ini": "[tox]\nrequires=somepkg123xyz\n[testenv:.tox]\nrunner=example"})
+    with pytest.raises(KeyError, match="example"):
+        proj.run("r", "-e", "py", "--result-json", str(log))