warn on ambiguous -p plugin module usage by yashwant86 · Pull Request #8 · Mergemonkey-demo/pytest

yashwant86 · 2026-04-07T21:03:28Z

Mirror of pytest-dev#14270

Summary by MergeMonkey

Documentation:
- Added changelog entry describing the new ambiguous plugin module warning
Just Shipped:
- Warns users when `-p` loads a module with no pytest hooks but a matching entry-point plugin exists, suggesting the correct plugin name

mergemonkeyhq · 2026-04-11T14:58:24Z

⚡ Risk Assessment — NEEDS-TESTING · ~15 min review

Focus areas: plugin hook detection logic · entry-point scanning correctness · warning message accuracy

Assessment: Adds warning logic for ambiguous plugin module loading via -p flag.

Walkthrough

When a user runs pytest with --disable-plugin-autoload -p <module_name>, the system now checks whether the loaded module contains any pytest hook implementations. If it doesn't, it scans all installed pytest11 entry-points for ones whose module path starts with the given module name, and emits a warning suggesting the correct -p name to use instead.

Changes

Files	Summary
Changelog `changelog/14135.bugfix.rst`	New changelog entry documenting the ambiguous `-p` plugin module warning behavior.
Ambiguous plugin detection logic `src/_pytest/config/__init__.py`	Introduces `_warn_about_submodule_entrypoint_plugin` to detect when `-p` loads a module lacking pytest hooks while a `pytest11` entry-point with a submodule path exists, and `_plugin_has_pytest_hooks` to introspect whether a plugin defines any hook implementations. Emits a `PytestConfigWarning` suggesting the correct `-p` name.
Tests for ambiguous plugin warning `testing/test_config.py`	Adds five test cases covering: warning emitted for single and multiple submodule entry-points, no warning when the module has hooks, no warning when no matching submodule entry-point exists, and a direct unit test of the warning method.

Sequence Diagram

sequenceDiagram
    participant User
    participant Config as PytestPluginManager
    participant EntryPoints as importlib.metadata
    participant HookCheck as _plugin_has_pytest_hooks
    participant WarnMethod as _warn_about_submodule_entrypoint_plugin

    User->>Config: import_plugin(modname, consider_entry_points=True)
    Config->>Config: load_setuptools_entrypoints("pytest11", name=modname)
    alt entry-point loaded
        Config-->>User: return (plugin registered via entry-point)
    else no entry-point match
        Config->>Config: __import__(modname)
        Config->>Config: register(mod, modname)
        Config->>WarnMethod: _warn_about_submodule_entrypoint_plugin(modname, mod)
        WarnMethod->>HookCheck: _plugin_has_pytest_hooks(mod)
        alt module has hooks
            HookCheck-->>WarnMethod: True
            WarnMethod-->>Config: return (no warning)
        else module has no hooks
            HookCheck-->>WarnMethod: False
            WarnMethod->>EntryPoints: distributions()
            EntryPoints-->>WarnMethod: list of distributions with entry-points
            alt matching submodule entry-points found
                WarnMethod->>User: emit PytestConfigWarning with suggestion
            else no matching entry-points
                WarnMethod-->>Config: return (no warning)
            end
        end
    end

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Runs only when explicitly triggered.

mergemonkeyhq · 2026-04-11T14:58:54Z

src/_pytest/config/__init__.py

+            if ep.group == "pytest11"
+            and ep.name != modname
+            and isinstance(getattr(ep, "value", None), str)
+            and getattr(ep, "value").split(":", 1)[0].startswith(modname_prefix)


Iterates all installed distributions on every ambiguous check

importlib.metadata.distributions() scans all installed packages. This runs every time a -p loaded module has no hooks. Consider caching the result or using importlib.metadata.entry_points(group='pytest11') which is more targeted and faster on Python 3.12+.

mergemonkeyhq · 2026-04-11T14:58:55Z

src/_pytest/config/__init__.py

+            if ep.group == "pytest11"
+            and ep.name != modname
+            and isinstance(getattr(ep, "value", None), str)
+            and getattr(ep, "value").split(":", 1)[0].startswith(modname_prefix)


Double getattr call risks AttributeError on race

Line 920 checks getattr(ep, 'value', None) but line 921 calls getattr(ep, 'value') without default. If value is a property that could change or raise, this could throw. Use a single assignment: val = getattr(ep, 'value', None) then check isinstance(val, str) and val.split(...)....

mergemonkeyhq · 2026-04-11T14:58:56Z

Actionable Comments Posted: 2

🧹 Nitpick comments (1)

\`\_plugin\_has\_pytest\_hooks\` has no explicit return type path - src/_pytest/config/__init__.py (940)

The function relies on \`any\(\)\` which always returns bool, so it's correct. However, \`parse\_hookimpl\_opts\` may raise exceptions for certain attributes \(e.g., descriptors\). Consider wrapping with try/except to avoid unexpected failures during introspection.

🧾 Coverage Summary

✔️ Covered (3 files)

- changelog/14135.bugfix.rst
- src/_pytest/config/__init__.py
- testing/test_config.py

yashwant86 · 2026-04-11T15:01:00Z

/review --force

mergemonkeyhq · 2026-04-11T15:03:27Z

Actionable Comments Posted: 0

👀 Worth a Look (1)

[MEDIUM] Hook detection can still raise on exotic plugin attributes - src/_pytest/config/__init__.py (938)

The new warning path calls \`\_plugin\_has\_pytest\_hooks\(\)\` on every \`-p\` module import that didn't resolve through entry points. That helper walks \`dir\(plugin\)\` and then \`parse\_hookimpl\_opts\(\)\` does an unguarded \`getattr\(plugin, name\)\` for every \`pytest\_\*\` attribute, so a plugin exposing a problematic descriptor/property can now fail during warning detection instead of just being imported.

Wrap the hook probe in a small \`try/except Exception\` around \`parse\_hookimpl\_opts\(\)\`/\`getattr\`, or limit detection to safe attribute sources for modules so the warning path can't break plugin import.

🧹 Nitpick comments (1)

Entry-point \`value\` is read twice in the new suggestion filter - src/_pytest/config/__init__.py (920)

The suggestion scan guards \`getattr\(ep, "value", None\)\` and then immediately reads \`getattr\(ep, "value"\)\` again. For normal \`importlib.metadata.EntryPoint\` objects that's fine, but the code now assumes repeated access is stable; a custom entry-point-like object with a property or side effect can pass the first check and fail or change on the second.

Store \`value = getattr\(ep, "value", None\)\` once inside the loop/comprehension and use that cached value for both the type check and split.

🧾 Coverage Summary

✔️ Covered (3 files)

- changelog/14135.bugfix.rst
- src/_pytest/config/__init__.py
- testing/test_config.py

kartikdp and others added 6 commits March 7, 2026 00:49

warn on ambiguous -p plugin module usage

f0192b9

tests: cover plugin warning branches for -p

6d288ce

tests: exercise direct plugin warning helper

9fb25c8

tests: avoid uncovered dummy entry-point methods

c92d067

config: keep plugin warning on one executable line

c19bda1

tests: avoid uncovered noop hook body

7dd52bf

mergemonkeyhq bot reviewed Apr 11, 2026

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warn on ambiguous -p plugin module usage#8

warn on ambiguous -p plugin module usage#8
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pr-14270

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Summary by MergeMonkey

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Walkthrough

Changes

Sequence Diagram

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mergemonkeyhq bot commented Apr 11, 2026

Actionable Comments Posted: 2

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yashwant86 commented Apr 7, 2026 •

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