[DONTMERGE] refactor: clean up node constructors — move logic to from_parent by RonnyPfannschmidt · Pull Request #14227 · pytest-dev/pytest

RonnyPfannschmidt · 2026-02-22T21:37:44Z

Summary

Moves initialization logic out of node __init__ methods and into from_parent, completing the refactoring that NodeMeta was designed to enable (see src/_pytest/nodes.py docstring on NodeMeta).

After this change, __init__ methods are "dumb stores" focused on assigning attributes, while from_parent methods handle derivation, validation, and post-construction setup.

Changes by node class

Item: Diamond inheritance check (_check_item_and_collector_diamond_inheritance) moved from __init__ to from_parent; converted to classmethod
Package: Removed redundant __init__ (only did session = parent.session, already handled by FSCollector); added explicit typed from_parent
FSCollector: Extracted _derive_name / _derive_nodeid as classmethods; from_parent pre-computes name and nodeid; __init__ retains fallback for non-cooperative constructors
DoctestItem: Fixture resolution (getfixtureinfo, _initrequest) moved from __init__ to from_parent
Function: Marker extension, keyword updates, fixture resolution, and _initrequest extracted into _setup_markers_and_fixtures, called from from_parent
Review fix: Eliminated double _imply_path call that would produce duplicate deprecation warnings; cleaned up dead __init__ parameters

What was NOT changed

Node.__init__ config/session/path/nodeid derivation was left in place — pushing these into from_parent as kwargs breaks backward compat for plugins with non-cooperative constructors (the NodeMeta._create fallback filters unknown kwargs, causing TypeErrors). The derivation is trivially parent.config/parent.session, and from_parent already enforces callers can't override them.

Test plan

Full test suite passes: 4032 passed, 45 skipped, 17 xfailed, 4 xpassed
All pre-commit hooks pass (ruff, mypy, codespell, etc.)
Key test files verified: test_nodes.py, test_collection.py, deprecated_test.py, python/collect.py, python/metafunc.py, test_doctest.py, test_runner.py, test_skipping.py, test_unittest.py, test_mark.py, test_junitxml.py

Note

This PR was AI-generated using Cursor with Claude (Anthropic). All commits include Co-authored-by attribution for both Cursor AI and Anthropic Claude.

Made with Cursor

… Item.from_parent The _check_item_and_collector_diamond_inheritance validation is not data storage — it's a one-time class-level check. Moving it to from_parent keeps __init__ focused on storing values. Also converts the method to a classmethod since it only inspects the class, not the instance. Co-authored-by: Cursor AI <ai@cursor.sh> Co-authored-by: Anthropic Claude <claude@anthropic.com>

…m_parent Package.__init__ only did `session = parent.session` which FSCollector already handles. Removing the __init__ entirely and adding an explicit from_parent with a typed signature for clarity. Also removes the now-unused LEGACY_PATH import from python.py. Co-authored-by: Cursor AI <ai@cursor.sh> Co-authored-by: Anthropic Claude <claude@anthropic.com>

…smethods and from_parent Extracts _derive_name and _derive_nodeid as classmethods on FSCollector. The from_parent method now pre-computes name and nodeid before calling super, so __init__ receives fully resolved values in the normal path. The __init__ retains fallback derivation for backward compatibility with non-cooperative constructors (plugins using positional args). Co-authored-by: Cursor AI <ai@cursor.sh> Co-authored-by: Anthropic Claude <claude@anthropic.com>

…to from_parent DoctestItem.__init__ now only stores runner, dtest, and obj. The fixture resolution (getfixtureinfo) and _initrequest() are moved to from_parent, which is the only production entry point for creating DoctestItem instances. Co-authored-by: Cursor AI <ai@cursor.sh> Co-authored-by: Anthropic Claude <claude@anthropic.com>

…nit__ to from_parent Function.__init__ now only stores _obj, _instance, originalname, and callspec. The marker extension, keyword updates, fixture resolution (getfixtureinfo), and _initrequest() are extracted into a new _setup_markers_and_fixtures method called from from_parent after construction. This keeps __init__ focused on storing values while from_parent handles all post-construction initialization logic. Co-authored-by: Cursor AI <ai@cursor.sh> Co-authored-by: Anthropic Claude <claude@anthropic.com>

1. FSCollector: fix double _imply_path call that would produce duplicate deprecation warnings when fspath is used. Now __init__ skips the _imply_path call when path is already resolved (by from_parent), using _check_path for consistency validation instead. 2. Function: remove dead keywords/fixtureinfo parameters from __init__ since from_parent now pops them before calling super. Replace with **kw for forward-compatibility with additional kwargs. Co-authored-by: Cursor AI <ai@cursor.sh> Co-authored-by: Anthropic Claude <claude@anthropic.com>

RonnyPfannschmidt · 2026-02-23T09:52:44Z

moved to rfr to trigger copilot review - this one is likely to need more iteration

Copilot

Pull request overview

Refactors pytest node construction so that initialization/derivation logic happens in from_parent, keeping __init__ methods closer to “attribute stores” and reducing side effects during object construction.

Changes:

Updated FSCollector to pre-compute path, name, and nodeid in from_parent, and avoid duplicate fspath deprecation warnings.
Moved Item’s diamond-inheritance warning to Item.from_parent.
Moved fixture/marker setup out of Function/DoctestItem.__init__ into from_parent, and replaced Package.__init__ with an explicit Package.from_parent.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
`src/_pytest/python.py`	Refactors `Package` construction and moves `Function` fixture/marker setup into `from_parent`.
`src/_pytest/nodes.py`	Refactors `FSCollector` name/nodeid derivation into helpers and `from_parent`; moves Item diamond check into `from_parent`.
`src/_pytest/doctest.py`	Moves doctest fixture initialization from `__init__` into `DoctestItem.from_parent`.

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Copilot · 2026-02-23T09:58:18Z

src/_pytest/python.py

+    @classmethod
+    def from_parent(  # type: ignore[override]
+        cls,
        parent: nodes.Collector,
-        # NOTE: following args are unused:
-        config=None,
-        session=None,
-        nodeid=None,
-        path: Path | None = None,
-    ) -> None:
-        # NOTE: Could be just the following, but kept as-is for compat.
-        # super().__init__(self, fspath, parent=parent)
-        session = parent.session
-        super().__init__(
-            fspath=fspath,
-            path=path,
-            parent=parent,
-            config=config,
-            session=session,
-            nodeid=nodeid,
-        )
+        *,
+        path: Path,
+    ) -> Self:
+        """The public constructor.
+
+        :param parent: The parent collector of this Package.
+        :param path: The package directory's path.
+        :type path: pathlib.Path
+        """
+        return super().from_parent(parent=parent, path=path)


Package.from_parent overrides Directory/FSCollector.from_parent but drops the fspath keyword entirely. This is a runtime API break: external code/plugins that still call Package.from_parent(..., fspath=...) (even if deprecated) will now get TypeError: got an unexpected keyword argument 'fspath'. Consider keeping fspath: LEGACY_PATH | None = None (and optionally path: Path | None = None) in the signature and delegating to super().from_parent(...) after resolving/validating, so deprecated callers continue to work while steering new code to path.

Copilot · 2026-02-23T09:58:18Z

src/_pytest/python.py

        If given, the object which will be called when the Function is invoked,
        otherwise the callobj will be obtained from ``parent`` using ``originalname``.
    :param keywords:
        Keywords bound to the function object for "-k" matching.
    :param session:
        The pytest Session object.
    :param fixtureinfo:
        Fixture information already resolved at this fixture node..
    :param originalname:
        The attribute name to use for accessing the underlying function object.
        Defaults to ``name``. Set this if name is different from the original name,
        for example when it contains decorations like those added by parametrization
        (``my_func[my_param]``).
    """

    # Disable since functions handle it themselves.
    _ALLOW_MARKERS = False

    def __init__(
        self,
        name: str,
        parent,
        config: Config | None = None,
        callspec: CallSpec2 | None = None,
        callobj=NOTSET,
-        keywords: Mapping[str, Any] | None = None,
        session: Session | None = None,
-        fixtureinfo: FuncFixtureInfo | None = None,
        originalname: str | None = None,
+        **kw,
    ) -> None:


The Function class docstring still documents keywords and fixtureinfo as constructor parameters, but __init__ no longer accepts them explicitly (they’re now handled in from_parent). This makes the public API docs misleading. Please update the docstring (or add a note) to reflect that keywords/fixtureinfo are from_parent kwargs and not __init__ parameters anymore.

RonnyPfannschmidt and others added 6 commits February 22, 2026 20:01

RonnyPfannschmidt marked this pull request as ready for review February 23, 2026 09:52

Copilot AI review requested due to automatic review settings February 23, 2026 09:52

Copilot started reviewing on behalf of RonnyPfannschmidt February 23, 2026 09:52 View session

RonnyPfannschmidt changed the title ~~refactor: clean up node constructors — move logic to from_parent~~ [DONTMERGE] refactor: clean up node constructors — move logic to from_parent Feb 23, 2026

Copilot AI reviewed Feb 23, 2026

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[DONTMERGE] refactor: clean up node constructors — move logic to from_parent#14227

[DONTMERGE] refactor: clean up node constructors — move logic to from_parent#14227
RonnyPfannschmidt wants to merge 6 commits intopytest-dev:mainfrom
RonnyPfannschmidt:cleanup/node-constructors-to-from-parent

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RonnyPfannschmidt commented Feb 22, 2026

Summary

Changes by node class

What was NOT changed

Test plan

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