Separate list dependencies to a separate installer class (#3347)

docs/changelog/3347.feature.rst

@@ -0,0 +1,2 @@
+Separate the list dependencies functionality to a separate abstract class allowing code reuse in plugins (such as
+``tox-uv``) - by :gaborbernat`.

src/tox/tox_env/python/pip/pip_install.py

@@ -2,6 +2,7 @@
 
 import logging
 import operator
+from abc import ABC, abstractmethod
 from collections import defaultdict
 from pathlib import Path
 from typing import TYPE_CHECKING, Any, Callable, Sequence
@@ -21,14 +22,36 @@
     from tox.tox_env.package import PathPackage
 
 
-class Pip(Installer[Python]):
-    """Pip is a python installer that can install packages as defined by PEP-508 and PEP-517."""
-
+class PythonInstallerListDependencies(Installer[Python], ABC):
     def __init__(self, tox_env: Python, with_list_deps: bool = True) -> None:  # noqa: FBT001, FBT002
         self._with_list_deps = with_list_deps
         super().__init__(tox_env)
 
     def _register_config(self) -> None:
+        if self._with_list_deps:  # pragma: no branch
+            self._env.conf.add_config(
+                keys=["list_dependencies_command"],
+                of_type=Command,
+                default=Command(self.freeze_cmd()),
+                desc="command used to list installed packages",
+            )
+
+    @abstractmethod
+    def freeze_cmd(self) -> list[str]:
+        raise NotImplementedError
+
+    def installed(self) -> list[str]:
+        cmd: Command = self._env.conf["list_dependencies_command"]
+        result = self._env.execute(cmd=cmd.args, stdin=StdinSource.OFF, run_id="freeze", show=False)
+        result.assert_success()
+        return result.out.splitlines()
+
+
+class Pip(PythonInstallerListDependencies):
+    """Pip is a python installer that can install packages as defined by PEP-508 and PEP-517."""
+
+    def _register_config(self) -> None:
+        super()._register_config()
         self._env.conf.add_config(
             keys=["pip_pre"],
             of_type=bool,
@@ -54,13 +77,9 @@ def _register_config(self) -> None:
             default=False,
             desc="Use the exact versions of installed deps as constraints, otherwise use the listed deps.",
         )
-        if self._with_list_deps:  # pragma: no branch
-            self._env.conf.add_config(
-                keys=["list_dependencies_command"],
-                of_type=Command,
-                default=Command(["python", "-m", "pip", "freeze", "--all"]),
-                desc="command used to list installed packages",
-            )
+
+    def freeze_cmd(self) -> list[str]:  # noqa: PLR6301
+        return ["python", "-m", "pip", "freeze", "--all"]
 
     def default_install_command(self, conf: Config, env_name: str | None) -> Command:  # noqa: ARG002
         isolated_flag = "-E" if self._env.base_python.version_info.major == 2 else "-I"  # noqa: PLR2004
@@ -82,12 +101,6 @@ def post_process_install_command(self, cmd: Command) -> Command:
                 install_command.pop(opts_at)
         return cmd
 
-    def installed(self) -> list[str]:
-        cmd: Command = self._env.conf["list_dependencies_command"]
-        result = self._env.execute(cmd=cmd.args, stdin=StdinSource.OFF, run_id="freeze", show=False)
-        result.assert_success()
-        return result.out.splitlines()
-
     def install(self, arguments: Any, section: str, of_type: str) -> None:
         if isinstance(arguments, PythonDeps):
             self._install_requirement_file(arguments, section, of_type)
@@ -239,4 +252,7 @@ def build_install_cmd(self, args: Sequence[str]) -> list[str]:
         return install_command[:opts_at] + list(args) + install_command[opts_at + 1 :]
 
 
-__all__ = ("Pip",)
+__all__ = [
+    "Pip",
+    "PythonInstallerListDependencies",
+]

src/tox/tox_env/python/runner.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+from abc import ABC
 from functools import partial
 from typing import TYPE_CHECKING, Set
 
@@ -16,11 +17,13 @@
 from .api import Python
 
 if TYPE_CHECKING:
+    from tox.config.cli.parser import Parsed
+    from tox.config.sets import CoreConfigSet, EnvConfigSet
     from tox.tox_env.api import ToxEnvCreateArgs
     from tox.tox_env.package import Package
 
 
-class PythonRun(Python, RunToxEnv):
+class PythonRun(Python, RunToxEnv, ABC):
     def __init__(self, create_args: ToxEnvCreateArgs) -> None:
         super().__init__(create_args)
 
@@ -34,19 +37,7 @@ def register_config(self) -> None:
             default=PythonDeps("", root),
             desc="Name of the python dependencies as specified by PEP-440",
         )
-
-        def skip_missing_interpreters_post_process(value: bool) -> bool:  # noqa: FBT001
-            if getattr(self.options, "skip_missing_interpreters", "config") != "config":
-                return StrConvert().to_bool(self.options.skip_missing_interpreters)
-            return value
-
-        self.core.add_config(
-            keys=["skip_missing_interpreters"],
-            default=True,
-            of_type=bool,
-            post_process=skip_missing_interpreters_post_process,
-            desc="skip running missing interpreters",
-        )
+        add_skip_missing_interpreters_to_core(self.core, self.options)
 
     @property
     def _package_types(self) -> tuple[str, ...]:
@@ -77,18 +68,7 @@ def _register_package_conf(self) -> bool:
         if pkg_type == "skip":
             return False
 
-        def _normalize_extras(values: set[str]) -> set[str]:
-            # although _ and . is allowed this will be normalized during packaging to -
-            # https://packaging.python.org/en/latest/specifications/dependency-specifiers/#grammar
-            return {canonicalize_name(v) for v in values}
-
-        self.conf.add_config(
-            keys=["extras"],
-            of_type=Set[str],
-            default=set(),
-            desc="extras to install of the target package",
-            post_process=_normalize_extras,
-        )
+        add_extras_to_env(self.conf)
         return True
 
     @property
@@ -122,3 +102,40 @@ def _build_packages(self) -> list[Package]:
                 msg = f"{exception.args[0]} for package environment {package_env.conf['env_name']}"
                 raise Skip(msg) from exception
         return packages
+
+
+def add_skip_missing_interpreters_to_core(core: CoreConfigSet, options: Parsed) -> None:
+    def skip_missing_interpreters_post_process(value: bool) -> bool:  # noqa: FBT001
+        if getattr(options, "skip_missing_interpreters", "config") != "config":
+            return StrConvert().to_bool(options.skip_missing_interpreters)
+        return value
+
+    core.add_config(
+        keys=["skip_missing_interpreters"],
+        default=True,
+        of_type=bool,
+        post_process=skip_missing_interpreters_post_process,
+        desc="skip running missing interpreters",
+    )
+
+
+def add_extras_to_env(conf: EnvConfigSet) -> None:
+    def _normalize_extras(values: set[str]) -> set[str]:
+        # although _ and . is allowed this will be normalized during packaging to -
+        # https://packaging.python.org/en/latest/specifications/dependency-specifiers/#grammar
+        return {canonicalize_name(v) for v in values}
+
+    conf.add_config(
+        keys=["extras"],
+        of_type=Set[str],
+        default=set(),
+        desc="extras to install of the target package",
+        post_process=_normalize_extras,
+    )
+
+
+__all__ = [
+    "PythonRun",
+    "add_extras_to_env",
+    "add_skip_missing_interpreters_to_core",
+]