Fix: exact text matching empty target

[Joel (aspire488)]

Description

Tests and Documentation

Description

Fixes an edge case in "ExactTextMatching" where an empty or whitespace-only target could incorrectly produce a match.

Python treats an empty string as being contained in every string (""" in text"), so an empty target could result in a false positive. This is particularly relevant when matching values that may default to an empty string.

Changes

• Reject empty targets in "ExactTextMatching.is_match()".
• Normalize whitespace before checking whether the target is empty.
• Add regression coverage for both empty and whitespace-only targets.

Related Issue

Closes #2881

Validation

Added unit tests covering:

• "target="""
• "target=" \n ""

Non-empty matching behavior remains unchanged.

[Joel (aspire488)]

Thank you for reviewing and merging this! Really appreciate the thoughtful feedback throughout the process.

It’s been great contributing to PyRIT, and I’m looking forward to continuing to work on improvements and picking up more issues in the future.