feat(assertions): re-add some lost assertions

[thomhurst]

Fixes #3462

[claude]

Claude finished @thomhurst's task —— View job

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Code Review for PR #3467

I'll review this PR that re-adds lost assertions that were accidentally removed.

Todo List:

• Read repository guidelines (CLAUDE.md)
• Analyze the changed files to understand what assertions were re-added
• Review assertion implementations for correctness and best practices
• Check test coverage and test quality
• Review public API changes
• Identify potential bugs, performance issues, or security concerns
• Provide comprehensive feedback

---

Summary

This PR restores several assertion methods that were previously lost, including boolean assertions, null/default checks, collection utilities, and string nullability checks. The changes look correct and follow TUnit's established patterns.

✅ Strengths

1. Consistent API Design: All re-added assertions follow TUnit's fluent assertion pattern
2. Good Test Coverage: Comprehensive tests added for boolean, default, and string nullability assertions
3. Proper Generic Constraints: HasDistinctItemsAssertion correctly updated to use <TCollection, TItem> generics with appropriate constraints
4. Source Generation: Boolean assertions properly use [GenerateAssertion] attributes for code generation
5. Nullability Support: Proper handling of nullable types in boolean and default assertions
6. Public API Verification: All changes properly reflected in API snapshot files

⚠️ Areas for Improvement

Performance Considerations

File: TUnit.Assertions/Conditions/HasDistinctItemsAssertion.cs:34-48

var list = value.ToList();
var distinctList = list.Distinct().ToList();

• Creates two lists from the enumerable, which could be expensive for large collections
• Consider using a HashSet-based approach for better performance:

var seenItems = new HashSet<TItem>();
var duplicates = new List<TItem>();
foreach (var item in value) {
    if (!seenItems.Add(item)) {
        duplicates.Add(item);
    }
}

Code Quality

File: TUnit.Assertions.Tests/BooleanAssertionTests.cs:1-2

using TUnit.Assertions.Extensions;
using TUnit.Assertions.Extensions; // Duplicate import

• Duplicate using statement should be removed

API Design

File: TUnit.Assertions/Conditions/NullAssertion.cs:97-98

if (EqualityComparer<TValue>.Default.Equals(value!, default!))

• Using null-forgiving operator (!) on potentially nullable values without null check
• The bang operators are technically safe here since we check for exceptions first, but could be clearer

🛡️ Security & Safety

• Thread Safety: ✅ All assertions are stateless and thread-safe
• Exception Handling: ✅ Proper exception handling in all assertion implementations
• Null Safety: ✅ Appropriate null checks and nullability annotations
• AOT Compatibility: ✅ No dynamic code generation that would break AOT

📋 Test Coverage Assessment

Excellent coverage provided for:

• Boolean assertions (both bool and bool?)
• Default value assertions for value types and reference types
• String nullability methods
• Error scenarios with exception assertions

Missing test coverage:

• HasDistinctItems assertion (no tests found in changed files)
• Edge cases like empty collections for distinct items check

🏗️ Architecture Alignment

✅ Follows TUnit patterns correctly:

• Dual-mode compatibility (source-gen + reflection)
• Proper base class inheritance from CollectionAssertionBase
• Consistent expression building for fluent APIs
• Source generation attributes used appropriately

🚀 Performance Impact

• Low impact: Most assertions are simple checks
• Potential concern: HasDistinctItems could be optimized for large collections
• Memory usage: Reasonable allocation patterns except for distinct items check

📝 Recommendations

1. Fix duplicate import in BooleanAssertionTests.cs
2. Optimize HasDistinctItems for better performance with large collections
3. Add tests for HasDistinctItems assertion to ensure it works correctly
4. Consider edge cases like empty collections and null items in distinct check

✅ Overall Assessment

This is a solid PR that correctly restores lost assertion functionality. The implementations are correct, well-tested, and follow established patterns. The only significant issue is a performance opportunity in HasDistinctItems. All changes maintain backward compatibility and properly update the public API surface.

Recommendation: Approve with minor suggested improvements.

---

[claude]

Claude finished @thomhurst's task —— View job

---

Code Review for PR #3467

I'll review this PR that re-adds lost assertions that were accidentally removed.

Todo List:

• Read repository guidelines (CLAUDE.md)
• Analyze the changed files to understand what assertions were re-added
• Review assertion implementations for correctness and best practices
• Check test coverage and test quality
• Review public API changes
• Identify potential bugs, performance issues, or security concerns
• Provide comprehensive feedback

---

Summary

This PR restores several assertion methods that were previously lost, including boolean assertions, null/default checks, collection utilities, and string nullability checks. The changes look correct and follow TUnit's established patterns.

✅ Strengths

1. Consistent API Design: All re-added assertions follow TUnit's fluent assertion pattern
2. Good Test Coverage: Comprehensive tests added for boolean, default, and string nullability assertions
3. Proper Generic Constraints: HasDistinctItemsAssertion correctly updated to use <TCollection, TItem> generics with appropriate constraints
4. Source Generation: Boolean assertions properly use [GenerateAssertion] attributes for code generation
5. Nullability Support: Proper handling of nullable types in boolean and default assertions
6. Public API Verification: All changes properly reflected in API snapshot files

⚠️ Areas for Improvement

Performance Considerations

File: TUnit.Assertions/Conditions/HasDistinctItemsAssertion.cs:34-48

var list = value.ToList();
var distinctList = list.Distinct().ToList();

• Creates two lists from the enumerable, which could be expensive for large collections
• Consider using a HashSet-based approach for better performance:

var seenItems = new HashSet<TItem>();
var duplicates = new List<TItem>();
foreach (var item in value) {
    if (!seenItems.Add(item)) {
        duplicates.Add(item);
    }
}

Code Quality

File: TUnit.Assertions.Tests/BooleanAssertionTests.cs:1-2

using TUnit.Assertions.Extensions;
using TUnit.Assertions.Extensions; // Duplicate import

• Duplicate using statement should be removed

API Design

File: TUnit.Assertions/Conditions/NullAssertion.cs:97-98

if (EqualityComparer<TValue>.Default.Equals(value!, default!))

• Using null-forgiving operator (!) on potentially nullable values without null check
• The bang operators are technically safe here since we check for exceptions first, but could be clearer

🛡️ Security & Safety

• Thread Safety: ✅ All assertions are stateless and thread-safe
• Exception Handling: ✅ Proper exception handling in all assertion implementations
• Null Safety: ✅ Appropriate null checks and nullability annotations
• AOT Compatibility: ✅ No dynamic code generation that would break AOT

📋 Test Coverage Assessment

Excellent coverage provided for:

• Boolean assertions (both bool and bool?)
• Default value assertions for value types and reference types
• String nullability methods
• Error scenarios with exception assertions

Missing test coverage:

• HasDistinctItems assertion (no tests found in changed files)
• Edge cases like empty collections for distinct items check

🏗️ Architecture Alignment

✅ Follows TUnit patterns correctly:

• Dual-mode compatibility (source-gen + reflection)
• Proper base class inheritance from CollectionAssertionBase
• Consistent expression building for fluent APIs
• Source generation attributes used appropriately

🚀 Performance Impact

• Low impact: Most assertions are simple checks
• Potential concern: HasDistinctItems could be optimized for large collections
• Memory usage: Reasonable allocation patterns except for distinct items check

📝 Recommendations

1. Fix duplicate import in BooleanAssertionTests.cs
2. Optimize HasDistinctItems for better performance with large collections
3. Add tests for HasDistinctItems assertion to ensure it works correctly
4. Consider edge cases like empty collections and null items in distinct check

✅ Overall Assessment

This is a solid PR that correctly restores lost assertion functionality. The implementations are correct, well-tested, and follow established patterns. The only significant issue is a performance opportunity in HasDistinctItems. All changes maintain backward compatibility and properly update the public API surface.

Recommendation: Approve with minor suggested improvements.

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