Use `ast.unparse` for generating patches with `lib_updater.py`#6142

ShaharNaveh

Summary by CodeRabbit

Refactor
- Overhauled patch generation to produce consistent, well-indented decorators and wrappers. Standardized indentation and formatting, and unified module checks for reliability.
Bug Fixes
- Correctly handles tests with or without arguments when extracting skip reasons and optional conditions. Normalizes reason text and reduces formatting errors by avoiding fragile string assembly across both patch phases.
Chores
- Streamlined loading and display of patches for clearer output. Introduced shared constants to align formatting across the tool.

coderabbitai

Walkthrough

Rewrites patch generation in scripts/lib_updater.py from string-based formatting to AST-driven decorator construction, adds UtMethod.has_args, refactors reason extraction logic to AST/surrounding-source paths, introduces new constants, updates JSON load/show handling, and standardizes indentation and unittest aliasing.

Changes

Cohort / File(s)	Summary of changes
AST-driven patch generation and extraction `scripts/lib_updater.py`	Replaced string fmt-based decorator generation with AST-based methods (`PatchSpec._attr_node`, `as_ast_node`, `as_decorator`, `_reason`); added `UtMethod.has_args`; revised Phase 1/2 emissions to use `as_decorator()` and `textwrap.indent` with `DEFAULT_INDENT`; updated reason/cond extraction via AST for arg-ful UT methods and surrounding source scan for arg-less; introduced `DEFAULT_INDENT`, `COMMENT`, `UT` alias; updated JSON load/show to handle `UtMethod` conversion and `spec._asdict()`; removed `PatchSpec.fmt`.

Sequence Diagram(s)

sequenceDiagram
    actor Dev as Developer/CLI
    participant LU as LibUpdater
    participant AST as Python AST
    participant SF as Source File
    participant JSON as Patches JSON

    rect rgb(235, 245, 255)
    note right of LU: Phase 1/2 Patch Emission (AST-driven)
    Dev->>LU: run update
    LU->>AST: build decorator nodes (PatchSpec.as_ast_node)
    AST-->>LU: ast.Attribute / ast.Call
    LU->>LU: render as_decorator() and indent with DEFAULT_INDENT
    LU->>SF: write decorators and wrappers
    end

    rect rgb(245, 235, 255)
    note right of LU: Patch Extraction (reason/cond)
    LU->>AST: parse source for UT methods
    alt UT method has_args()
        LU->>AST: walk dec_node for COMMENT string and optional cond
        AST-->>LU: reason, cond
    else No args
        LU->>SF: scan surrounding lines for COMMENT
        SF-->>LU: reason line
    end
    LU->>LU: normalize reason via removeprefix(COMMENT)
    end

    rect rgb(235, 255, 240)
    note right of LU: JSON I/O
    LU->>JSON: load patches
    JSON-->>LU: dicts
    LU->>LU: convert ut_method -> UtMethod via _replace
    LU-->>Dev: show-patches via spec._asdict()
    end

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~60 minutes

Possibly related PRs

Add tool for easier test updates #6089: Overlaps scripts/lib_updater.py, modifying PatchSpec/UtMethod and patch generation/extraction; likely part of or precursor to this AST-based refactor.

Suggested reviewers

reactive-firewall
youknowone

Pre-merge checks (1 passed, 1 warning, 1 inconclusive)

❌ Failed checks (1 warning, 1 inconclusive)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run `@coderabbitai generate docstrings` to improve docstring coverage.
Description Check	❓ Inconclusive	The pull request currently lacks a dedicated description outlining its scope or details, making it unclear how the changes align with project goals even though a raw summary is provided.	Please add a clear description summarizing the key changes and intent of the pull request so reviewers can quickly understand its purpose.

✅ Passed checks (1 passed)

Check name	Status	Explanation
Title Check	✅ Passed	The title succinctly captures the primary change—switching lib_updater.py’s patch generation to leverage ast.unparse—and is both concise and specific enough for teammates to quickly grasp the new implementation approach without extraneous detail.

Poem

A nibble of AST, a sprinkle of reason,
I hop through phases, patching in season.
No strings to fray—just nodes that align,
Indents in step, decorators divine.
With whiskers a-twitch, I merge and I test—
Hippity-hop, this update’s the best! 🐇✨

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Actionable comments posted: 3

🧹 Nitpick comments (2)

scripts/lib_updater.py (2)

149-149: Broaden detection of unittest alias (optional).

Matching only attr_node.value.id == "unittest" misses import unittest as ut. Consider collecting aliases from imports and/or allow a small alias set.

Example minimal tweak (constant-only):

-                    or getattr(attr_node.value, "id", None) != UT
+                    or getattr(attr_node.value, "id", None) not in {UT, "ut", "UT"}

Or, for correctness, scan imports to discover the actual alias and check against that alias. I can draft that if you want.

328-331: Slightly simplify JSON→PatchSpec load path (optional).

Avoid constructing then _replace; also tolerate missing keys.

Apply this diff:

-                test_name: [
-                    PatchSpec(**spec)._replace(ut_method=UtMethod(spec["ut_method"]))
-                    for spec in specs
-                ]
+                test_name: [
+                    PatchSpec(
+                        ut_method=UtMethod(spec["ut_method"]),
+                        cond=spec.get("cond"),
+                        reason=spec.get("reason", ""),
+                    )
+                    for spec in specs
+                ]

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Review profile: CHILL

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📥 Commits

Reviewing files that changed from the base of the PR and between 7044d43 and 1966c3e.

⛔ Files ignored due to path filters (6)

Lib/test/test_ast/test_ast.py is excluded by !Lib/**
Lib/test/test_csv.py is excluded by !Lib/**
Lib/test/test_logging.py is excluded by !Lib/**
Lib/test/test_os.py is excluded by !Lib/**
Lib/test/test_str.py is excluded by !Lib/**
Lib/test/test_xml_etree.py is excluded by !Lib/**

📒 Files selected for processing (1)

scripts/lib_updater.py (8 hunks)

🧰 Additional context used

📓 Path-based instructions (1)

**/*.py

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

**/*.py: Follow PEP 8 style for custom Python code
Use ruff for linting Python code

Files:

scripts/lib_updater.py

🧠 Learnings (1)

📓 Common learnings

Learnt from: ShaharNaveh
PR: RustPython/RustPython#6089
File: scripts/lib_updater.py:198-202
Timestamp: 2025-09-07T05:38:31.644Z
Learning: In scripts/lib_updater.py, the iter_patches function intentionally does not handle SyntaxError from ast.parse(contents). The author confirmed this behavior is fine and intended - the tool should fail fast on unparseable files rather than silently skip processing.

🪛 Flake8 (7.2.0)

scripts/lib_updater.py

[error] 41-41: SyntaxError: invalid syntax

(E999)

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🔇 Additional comments (2)

scripts/lib_updater.py (2)

243-245: Decorator emission and phase-2 wrapper formatting look good.

Switch to textwrap.indent and centralized DEFAULT_INDENT improves consistency and readability.

Also applies to: 253-260

35-35: Nice cleanup.

Importing textwrap, introducing DEFAULT_INDENT, centralizing UT, and adding _reason/has_args/as_decorator streamline formatting and reduce stringly-typed code.

Also applies to: 43-46, 57-59, 87-90, 106-113

ShaharNaveh added 11 commits September 9, 2025 11:03

Use ast.unparse for decorator generation

dd5661c

Cleanup code a bit

e0b7984

Use ast.unparse for every ut_method

25c5569

use textwrap

30d1294

Apply patches to test_os.py

efdcfcc

Apoly on test_xml_etree.py

4096e86

Ensure ut_method type for external patches

9633595

Run on some test files

bc8f77f

Mark failing test

aa50293

Update test_str.py

aa95d8f

Update test_logging.py from 3.13.7

1966c3e

ShaharNaveh commented Sep 9, 2025

View reviewed changes

coderabbitai Bot reviewed Sep 9, 2025

View reviewed changes

Merge remote-tracking branch 'upstream/main' into fix-lib-updater-bugs

b4bf5ec

youknowone approved these changes Sep 11, 2025

View reviewed changes

youknowone mentioned this pull request Dec 4, 2025

Update Python libraries and tests from Python 3.13 #5529

Closed

coderabbitai Bot mentioned this pull request Jan 10, 2026

preparing step to integrate fix_test into lib_updater #6698

Merged

coderabbitai Bot mentioned this pull request Jan 20, 2026

Remake update_lib #6796

Merged

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Use `ast.unparse` for generating patches with `lib_updater.py`#6142