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Fixes #3425

@claude
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claude bot commented Oct 17, 2025

Claude finished @thomhurst's task —— View job


PR Review: Assertion Validation Before Type Conversion

Overview

This PR addresses a critical bug where previous assertions in a chain were not being validated before type conversion operations like WhenParsedInto<T>() and IsTypeOf<T>(). The fix introduces a PendingPreWork mechanism to execute previous assertions before performing type conversions.

✅ Code Quality & Best Practices

Excellent implementation that follows TUnit's patterns:

  • Properly handles cross-type assertion chaining via PendingPreWork
  • Uses existing ConsumePendingLink() mechanism consistently
  • Minimal, focused changes that don't disrupt existing architecture
  • Good use of async/await patterns and proper exception handling
  • Code style follows established conventions (no comments, modern C# syntax)

✅ Bug Fix Analysis

The fix correctly addresses the root issue:

  • Problem: Assert.That("123").HasLength(4).And.WhenParsedInto<int>() would parse successfully even though HasLength(4) should fail
  • Solution: Store pending assertions as pre-work in type conversion constructors
  • Execution order: Pre-work assertions execute in ExecuteCoreAsync() before any type conversion logic

Key changes in Assertion.cs:121-127:

if (Context.PendingPreWork != null)
{
    await Context.PendingPreWork();
    Context.PendingPreWork = null; // Execute only once
}

✅ Test Coverage

Comprehensive test suite covering edge cases:

  • Parse assertions: Tests both successful and failing chains with WhenParsedInto<T>()
  • Type assertions: Tests IsTypeOf<T>() with various object-to-string scenarios
  • Complex chains: Multiple assertions before and after type conversions
  • Assert.Multiple: Validates behavior in assertion scopes
  • Failure scenarios: Ensures correct assertion fails at the right time

Notable test examples:

  • WhenParsedInto_WithAnd_PreviousAssertion_ShouldFail - validates HasLength(4) fails before parsing "123"
  • IsTypeOf_WithAnd_NullCheck_ShouldFail - ensures null checks happen before type conversion
  • Complex chaining scenarios with multiple assertions

✅ Performance Considerations

Minimal performance impact:

  • Pre-work only executes when needed (cross-type chaining)
  • Single execution guaranteed via null assignment
  • No additional allocations or overhead for simple assertions
  • Leverages existing context mechanisms efficiently

✅ Security & Threading

No security concerns identified:

  • No reflection changes or new attack vectors
  • Thread-safe execution (assertions already handle concurrency)
  • Proper exception propagation and cleanup

✅ Architecture Adherence

Follows TUnit development guidelines:

  • Maintains dual-mode compatibility (source-gen and reflection)
  • Uses established assertion context patterns
  • Preserves existing API surface
  • Thread-safe and AOT-compatible

Minor Suggestions

  1. Documentation: Consider adding XML doc comments to PendingPreWork property explaining its purpose
  2. Error messages: Could potentially improve error messages to indicate when pre-work assertions fail vs. main assertions

Final Assessment

This is a high-quality fix that:

  • ✅ Correctly resolves the assertion ordering bug
  • ✅ Maintains backward compatibility
  • ✅ Includes comprehensive test coverage
  • ✅ Follows established patterns and conventions
  • ✅ Has minimal performance impact
  • ✅ Properly handles edge cases

Recommendation: Approve and merge - This is a clean, well-tested fix that addresses a real usability issue without introducing risks.


@thomhurst thomhurst enabled auto-merge (squash) October 17, 2025 13:18
@thomhurst thomhurst merged commit 2569223 into main Oct 17, 2025
12 of 13 checks passed
@thomhurst thomhurst deleted the bug/3425 branch October 17, 2025 13:43
This was referenced Oct 17, 2025
This was referenced Oct 22, 2025
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Assertions before conversion are not checked

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