pi-lens/rules/tree-sitter-queries/python/python-raise-string.yml

Real-time code feedback for pi — LSP, linters, formatters, type-checking, structural analysis & booboo

id: python-raise-string
name: Raise String Instead of Exception
severity: warning
category: reliability
defect_class: correctness
inline_tier: blocking
language: python

message: "raise with string literal — Python 3 requires exception instances"

description: |
  In Python 3, 'raise "message"' is a TypeError at runtime.
  You must raise exception instances or classes, not strings.
  
  ✅ FIX:
    raise ValueError("message")
    raise RuntimeError(f"failed: {reason}")

query: |
  (raise_statement
    (string) @VALUE)

metavars:
  - VALUE

has_fix: false

tags:
  - reliability
  - error-handling
  - python3

examples:
  bad: |
    if not valid:
        raise "Validation failed"   # TypeError in Python 3!
  
  good: |
    if not valid:
        raise ValueError("Validation failed")