[refurb] Fix annotated assignments blocking FURB101 fix (FURB101)

[danparizher]

Summary

Fixed FURB101 (read-whole-file) to handle annotated assignments. Previously, the rule would detect violations in code like contents: str = f.read() but fail to generate a fix. Now it correctly generates fixes that preserve type annotations (e.g., contents: str = Path("file.txt").read_text(encoding="utf-8")).

Fixes #21274

Problem Analysis

The FURB101 rule was only checking for Stmt::Assign statements when determining whether a fix could be applied. When encountering annotated assignments (Stmt::AnnAssign) like contents: str = f.read(), the rule would:

1. Correctly detect the violation (the diagnostic was reported)
2. Fail to generate a fix because:
   • The visit_expr method only matched Stmt::Assign, not Stmt::AnnAssign
   • The generate_fix function only accepted Stmt::Assign in its body validation
   • The replacement code generation didn't account for type annotations

This occurred because Python's AST represents annotated assignments as a different node type (StmtAnnAssign) with separate fields for the target, annotation, and value, unlike regular assignments which use a list of targets.

Approach

The fix extends the rule to handle both assignment types:

1. Updated visit_expr method: Now matches both Stmt::Assign and Stmt::AnnAssign, extracting:

   • Variable name from the target expression
   • Type annotation code (when present) using the code generator

2. Updated generate_fix function:

   • Added annotation: Option<String> parameter to accept annotation code
   • Updated body validation to accept both Stmt::Assign and Stmt::AnnAssign
   • Modified replacement code generation to preserve annotations: {var}: {annotation} = {binding}({filename_code}).{suggestion}

3. Added test case: Added an annotated assignment test case to verify the fix works correctly.

The implementation maintains backward compatibility with regular assignments while adding support for annotated assignments, ensuring type annotations are preserved in the generated fixes.

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

ℹ️ ecosystem check detected linter changes. (+0 -0 violations, +14 -0 fixes in 2 projects; 53 projects unchanged)

apache/airflow (+0 -0 violations, +2 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --no-fix --output-format concise --preview --select ALL

+ providers/amazon/src/airflow/providers/amazon/aws/hooks/base_aws.py:1005:18: FURB101 [*] `open` and `read` should be replaced by `Path(self.waiter_path).read_text()`
- providers/amazon/src/airflow/providers/amazon/aws/hooks/base_aws.py:1005:18: FURB101 `open` and `read` should be replaced by `Path(self.waiter_path).read_text()`

zulip/zulip (+0 -0 violations, +12 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --no-fix --output-format concise --preview --select ALL

+ zerver/lib/export.py:1729:10: FURB101 [*] `open` and `read` should be replaced by `Path(input_path).read_bytes()`
- zerver/lib/export.py:1729:10: FURB101 `open` and `read` should be replaced by `Path(input_path).read_bytes()`
+ zerver/lib/import_realm.py:1214:10: FURB101 [*] `open` and `read` should be replaced by `Path(migration_status_filename).read_text()`
- zerver/lib/import_realm.py:1214:10: FURB101 `open` and `read` should be replaced by `Path(migration_status_filename).read_text()`
+ zerver/lib/import_realm.py:998:10: FURB101 [*] `open` and `read` should be replaced by `Path(records_filename).read_bytes()`
- zerver/lib/import_realm.py:998:10: FURB101 `open` and `read` should be replaced by `Path(records_filename).read_bytes()`
+ zerver/lib/management.py:282:18: FURB101 [*] `open` and `read` should be replaced by `Path(options["password_file"]).read_text()`
- zerver/lib/management.py:282:18: FURB101 `open` and `read` should be replaced by `Path(options["password_file"]).read_text()`
+ zerver/management/commands/send_custom_email.py:118:22: FURB101 [*] `open` and `read` should be replaced by `Path(options["json_file"]).read_text()`
- zerver/management/commands/send_custom_email.py:118:22: FURB101 `open` and `read` should be replaced by `Path(options["json_file"]).read_text()`
+ zerver/management/commands/send_custom_email.py:233:18: FURB101 [*] `open` and `read` should be replaced by `Path(options["json_file"]).read_text()`
- zerver/management/commands/send_custom_email.py:233:18: FURB101 `open` and `read` should be replaced by `Path(options["json_file"]).read_text()`

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
FURB101	14	0	0	14	0