Display registered plugins with --version (#2413)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Bernát Gábor <gaborjbernat@gmail.com>

1 files changed, 36 insertions, 9 deletions

diff --git a/src/tox/session/cmd/version_flag.py b/src/tox/session/cmd/version_flag.py
index 52797b6e..cad1c3f9 100644
--- a/src/tox/session/cmd/version_flag.py
+++ b/src/tox/session/cmd/version_flag.py
@@ -3,19 +3,46 @@ Display the version information about tox.
 """
 from __future__ import annotations
 
+import sys
+from argparse import SUPPRESS, Action, ArgumentParser, Namespace
 from pathlib import Path
+from typing import Any, Sequence, cast
 
-from tox.config.cli.parser import ToxParser
+import tox
+from tox.config.cli.parser import HelpFormatter, ToxParser
 from tox.plugin import impl
+from tox.plugin.manager import MANAGER
+from tox.version import version
 
 
 @impl
 def tox_add_option(parser: ToxParser) -> None:
-    import tox
-    from tox.version import version
-
-    parser.add_argument(
-        "--version",
-        action="version",
-        version=f"{version} from {Path(tox.__file__).absolute()}",
-    )
+    class _V(Action):
+        def __init__(self, option_strings: Sequence[str], dest: str = SUPPRESS) -> None:
+            help_msg = "show program's and plugins version number and exit"
+            super().__init__(option_strings=option_strings, dest=dest, nargs=0, help=help_msg, default=SUPPRESS)
+
+        def __call__(
+            self,
+            parser: ArgumentParser,
+            namespace: Namespace,  # noqa: U100
+            values: str | Sequence[Any] | None,  # noqa: U100
+            option_string: str | None = None,  # noqa: U100
+        ) -> None:
+            formatter = cast(HelpFormatter, parser._get_formatter())
+            formatter.add_raw_text(get_version_info())
+            parser._print_message(formatter.format_help(), sys.stdout)
+            parser.exit()
+
+    parser.add_argument("--version", action=_V)
+
+
+def get_version_info() -> str:
+    out = [f"{version} from {Path(tox.__file__).absolute()}"]
+    plugin_info = MANAGER.manager.list_plugin_distinfo()
+    if plugin_info:
+        out.append("registered plugins:")
+        for module, egg_info in plugin_info:
+            source = getattr(module, "__file__", repr(module))
+            out.append(f"    {egg_info.project_name}-{egg_info.version} at {source}")
+    return "\n".join(out)