Extract packaging virtualenv code to its own class

Signed-off-by: Bernát Gábor <bgabor8@bloomberg.net>

docs/changelog/3200.feature.rst

@@ -0,0 +1 @@
+Extract virtual environment packaging code to its own base class not tied to ``virtualenv`` - by :user:`gaborbernat`.

src/tox/tox_env/python/virtual_env/package/cmd_builder.py

@@ -2,6 +2,7 @@
 
 import glob
 import tarfile
+from abc import ABC
 from functools import partial
 from io import TextIOWrapper
 from pathlib import Path
@@ -35,15 +36,11 @@
 from importlib.metadata import Distribution
 
 
-class VirtualEnvCmdBuilder(PythonPackageToxEnv, VirtualEnv):
+class VenvCmdBuilder(PythonPackageToxEnv, ABC):
     def __init__(self, create_args: ToxEnvCreateArgs) -> None:
         super().__init__(create_args)
         self._sdist_meta_tox_env: Pep517VirtualEnvPackager | None = None
 
-    @staticmethod
-    def id() -> str:
-        return "virtualenv-cmd-builder"
-
     def register_config(self) -> None:
         super().register_config()
         root = self.core["toxinidir"]
@@ -131,6 +128,12 @@ def child_pkg_envs(self, run_conf: EnvConfigSet) -> Iterator[PackageToxEnv]:  #
             yield self._sdist_meta_tox_env
 
 
+class VirtualEnvCmdBuilder(VenvCmdBuilder, VirtualEnv):
+    @staticmethod
+    def id() -> str:
+        return "virtualenv-cmd-builder"
+
+
 class WheelDistribution(Distribution):  # cannot subclass has type Any
     def __init__(self, wheel: Path) -> None:
         self._wheel = wheel

src/tox/tox_env/python/virtual_env/package/pyproject.py

@@ -3,6 +3,7 @@
 import logging
 import os
 import sys
+from abc import ABC
 from collections import defaultdict
 from contextlib import contextmanager
 from itertools import chain
@@ -94,8 +95,8 @@ def out_err(self) -> tuple[str, str]:
         return status.outcome.out_err()
 
 
-class Pep517VirtualEnvPackager(PythonPackageToxEnv, VirtualEnv):
-    """local file system python virtual environment via the virtualenv package."""
+class Pep517VenvPackager(PythonPackageToxEnv, ABC):
+    """local file system python virtual environment package builder."""
 
     def __init__(self, create_args: ToxEnvCreateArgs) -> None:
         super().__init__(create_args)
@@ -360,6 +361,14 @@ def requires(self) -> tuple[Requirement, ...]:
         return self._frontend.requires
 
 
+class Pep517VirtualEnvPackager(Pep517VenvPackager, VirtualEnv):
+    """local file system python virtual environment via the virtualenv package."""
+
+    @staticmethod
+    def id() -> str:
+        return "virtualenv-pep-517"
+
+
 class Pep517VirtualEnvFrontend(Frontend):
     def __init__(self, root: Path, env: Pep517VirtualEnvPackager) -> None:
         super().__init__(*Frontend.create_args_from_folder(root))