Allow plugins to attach data to --version

docs/changelog/3234.feature.rst

@@ -0,0 +1,2 @@
+Allow plugins attaching additional information to ``--version`` via ``tox_append_version_info`` method in the plugin
+module - by :user:`gaborbernat`.

docs/plugins.rst

@@ -14,6 +14,15 @@ Extensions points
 .. automodule:: tox.plugin.spec
    :members:
 
+A plugin can define its plugin module a:
+
+.. code-block:: python
+
+   def tox_append_version_info() -> str:
+       return "magic"
+
+and this message will be appended to the output of the ``--version`` flag.
+
 Adoption of a plugin under tox-dev Github organization
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

src/tox/session/cmd/version_flag.py

@@ -43,5 +43,7 @@ def get_version_info() -> str:
         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}")
+            info = module.tox_append_version_info() if hasattr(module, "tox_append_version_info") else ""
+            with_info = f" {info}" if info else ""
+            out.append(f"    {egg_info.project_name}-{egg_info.version} at {source}{with_info}")
     return "\n".join(out)

tests/test_version.py

@@ -26,10 +26,13 @@ def test_version_without_plugin(tox_project: ToxProjectCreator) -> None:
 def test_version_with_plugin(tox_project: ToxProjectCreator, mocker: MockFixture) -> None:
     dist = [
         (
-            mocker.create_autospec("types.ModuleType", __file__=f"{i}-path"),
-            SimpleNamespace(project_name=i, version=v),
-        )
-        for i, v in (("B", "1.0"), ("A", "2.0"))
+            mocker.create_autospec("types.ModuleType", __file__="B-path", tox_append_version_info=lambda: "magic"),
+            SimpleNamespace(project_name="B", version="1.0"),
+        ),
+        (
+            mocker.create_autospec("types.ModuleType", __file__="A-path"),
+            SimpleNamespace(project_name="A", version="2.0"),
+        ),
     ]
     mocker.patch.object(MANAGER.manager, "list_plugin_distinfo", return_value=dist)
 
@@ -42,6 +45,6 @@ def test_version_with_plugin(tox_project: ToxProjectCreator, mocker: MockFixture
 
     assert lines[1:] == [
         "registered plugins:",
-        "    B-1.0 at B-path",
+        "    B-1.0 at B-path magic",
         "    A-2.0 at A-path",
     ]