@kroitlory

Validation and Regex Compatibility Issues in python-string-utils

Summary

Several validation functions appear to reject inputs that are commonly accepted in standard formats. Property-based and targeted tests reveal at least three distinct issues:

• Scientific notation support in is_number/is_decimal is incomplete (rejects uppercase E and negative exponents)
• URL port parsing is overly restrictive (rejects single-digit ports)
• Pangram detection is case-sensitive (fails uppercase-only pangrams)

Affected Code

• Scientific notation regex: string_utils/_regex.py:7
• URL regex port segment: string_utils/_regex.py:14
• Pangram implementation: string_utils/validation.py:510-514
• Number validation: string_utils/validation.py:135-138
• Decimal validation: string_utils/validation.py:159-172

Environment

• OS: Windows
• Python: 3.10
• Command: python run_added_tests.py

Expected Behavior

• is_number and is_decimal should accept scientific notation using both lowercase and uppercase E, and should allow signed exponents (e.g., 1e-3, 1E+3, 1.5e-3).
• is_url should accept 1–5 digit port numbers (standard range 0–65535), e.g., http://localhost:8.
• is_pangram should be case-insensitive (uppercase-only pangrams should pass).

Actual Behavior

• Scientific notation:
  • is_number('1E3') → False
  • is_number('1e-3') → False
  • is_decimal('1.5e-3') → False
• URL port:
  • is_url('http://localhost:8') → False
  • is_url('http://127.0.0.1:7') → False
• Pangram:
  • is_pangram('THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG') → False

Code References

• Scientific notation regex currently: string_utils/_regex.py:7
  • NUMBER_RE = re.compile(r'^([+\-]?)((\d+)(\.\d+)?(e\d+)?|\.\d+)$')
  • Limitations:
    • Only lowercase e
    • Exponent requires digits only (\d+), no optional sign
• URL port segment: string_utils/_regex.py:14
  • (:\d{2,})? requires at least two digits for the port
• Pangram: string_utils/validation.py:510-514
  • Compares set of characters to string.ascii_lowercase without case normalization

Suggested Fixes

• is_number / is_decimal:
  • Update NUMBER_RE to accept both e and E, and an optional sign before exponent digits, e.g.:
    • Allow pattern segment like [eE][+\-]?\d+
  • Ensure downstream checks (is_integer, is_decimal) keep consistent semantics when scientific notation is used.
• is_url:
  • Relax port segment to (:\d{1,5})? and optionally validate numeric range (0–65535) outside the regex if desired.
• is_pangram:
  • Normalize input to lowercase (or use a case-insensitive comparison) before computing set inclusion.