Ignore labels when provisioning (#2917)

Fix #2916

Author: masenf

docs/changelog/2916.bugfix.rst

@@ -0,0 +1,3 @@
+Ignore labels when tox will provision a runtime environment (``.tox``) so that environment configurations which depend
+on provisioned plugins or specific tox versions are not accessed in the outer tox process where the configuration would
+be invalid - by :user:`masenf`.

src/tox/session/env_select.py

@@ -315,7 +315,8 @@ def _mark_active(self) -> None:
         if labels or factors:
             for env_info in self._defined_envs_.values():
                 env_info.is_active = False  # if any was selected reset
-            if labels:
+            # ignore labels when provisioning will occur
+            if labels and (self._provision is None or not self._provision[0]):
                 for label in labels:
                     for env_name in self._state.conf.core["labels"].get(label, []):
                         self._defined_envs_[env_name].is_active = True

tests/test_provision.py

@@ -195,14 +195,21 @@ def test_provision_no_recreate_json(tox_project: ToxProjectCreator) -> None:
 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()
+    proj = tox_project(
+        {"tox.ini": f"[tox]\nrequires=demo-pkg-inline\nlabels=l=py\n[{plugin_testenv}]\nrunner=example"},
+    )
     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
+
+    result_env = proj.run("r", "-e", "py", "--result-json", str(log))
+    result_env.assert_success()
+    assert prov_msg in result_env.out
+
+    result_label = proj.run("r", "-m", "l", "--result-json", str(log))
+    result_label.assert_success()
+    assert prov_msg in result_label.out
 
 
 @pytest.mark.integration()