fix: add WithMessageNotContaining assertion for exception messages

[thomhurst]

Fixes #3104

[claude]

Claude finished @thomhurst's task —— View job

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Code Review Complete ✅

Reviewing PR #3165: "fix: add WithMessageNotContaining assertion for exception messages"

Review Checklist:

• Read repository guidelines (CLAUDE.md)
• Analyze changed files and implementation
• Evaluate code quality and best practices
• Check for potential bugs or issues
• Assess performance considerations
• Review security concerns
• Evaluate test coverage
• Provide comprehensive feedback

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Summary

This PR adds a WithMessageNotContaining assertion method for exception messages, which is the logical inverse of the existing WithMessageContaining method. The implementation follows TUnit's established patterns and coding standards.

✅ Strengths

Code Quality & Best Practices:

• Consistent API Design: The new methods follow the exact same pattern as existing WithMessageContaining methods in ThrowsException.cs:53-65, providing both ordinal and custom StringComparison overloads
• Modern C# Usage: Uses primary constructors, file-scoped namespaces, and expression-bodied members as per TUnit standards
• Proper Naming: Method and class names follow established conventions and are descriptive
• Code Reuse: Leverages existing extension methods like PrependAOrAn(), ShowNewLines(), and TruncateWithEllipsis(100)

Implementation Consistency:

• Mirror Pattern: ThrowsWithMessageNotContainingAssertCondition.cs perfectly mirrors ThrowsWithMessageContainingAssertCondition.cs with only the logical inverse (lines 25-26)
• Error Messages: Expectation message follows the established pattern: "to throw {ExceptionType} which message does not contain "{expected}""
• CallerArgumentExpression: Properly uses [CallerArgumentExpression] attributes for better debugging experience

Test Coverage:

• Comprehensive Testing: Tests cover all scenarios in ThrowInDelegateValueAssertionTests.cs:42-103:
  • ✅ Positive case: message doesn't contain text (passes)
  • ✅ Negative case: message contains text (fails with proper error message)
  • ✅ Case sensitivity with StringComparison.OrdinalIgnoreCase
  • ✅ Case sensitivity with StringComparison.Ordinal
• Error Message Validation: Test on lines 68-70 verifies the assertion failure message contains the expected text

🔍 Technical Analysis

Performance:

• ✅ Zero Performance Impact: Uses the same string comparison logic as existing methods
• ✅ Efficient Logic: Uses !actualException.Message.Contains() instead of complex string operations
• ✅ Minimal Allocations: Reuses existing extension methods for formatting

Security:

• ✅ No Security Concerns: Simple string comparison logic with no external dependencies
• ✅ Input Validation: Properly handles null exceptions and null expected values

Potential Issues:

• ✅ Null Safety: Lines 23-26 in ThrowsWithMessageNotContainingAssertCondition.cs properly handle null exceptions
• ✅ API Consistency: Both overloads match the existing WithMessageContaining pattern exactly

Public API Changes:

• ✅ Snapshot Updates: All three target framework API snapshots (.NET 4.7, .NET 8.0, .NET 9.0) have been properly updated
• ✅ Non-Breaking: Only adds new methods without modifying existing APIs

📋 Repository Compliance

TUnit Guidelines Adherence:

• ✅ Code Standards: Follows modern C# patterns, proper casing, and expression-bodied members
• ✅ Performance Focus: No performance regressions introduced
• ✅ Testing: Comprehensive test coverage for the new functionality
• ✅ API Snapshots: Properly accepted snapshot changes as required by CLAUDE.md guidelines

🎯 Verdict

APPROVED - This is a well-implemented feature that:

• Adds useful functionality (inverse of existing WithMessageContaining)
• Follows all established patterns and conventions
• Includes comprehensive test coverage
• Has zero performance impact
• Maintains API consistency

The implementation is clean, follows TUnit's high standards, and provides a logical complement to the existing assertion methods.

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