WPF HexEditor - Unit Tests

Comprehensive unit tests for WPF HexEditor performance optimizations using xUnit.

📊 Test Coverage

SpanSearchExtensionsTests (18 tests)

Tests for high-performance Span search extensions.

Coverage:

• FindIndexOf() - Pattern matching in Span
  • Single occurrence
  • Multiple occurrences
  • Overlapping matches
  • Edge cases (empty data, empty pattern, pattern longer than data)
  • Base offset application
• FindFirstIndexOf() - First-match optimization
  • Early termination
  • Base offset
  • No-match scenarios
• CountOccurrences() - Zero-allocation counting
  • Correct counting
  • Empty patterns
  • No-match scenarios

Status: ✅ All 18 tests passing

ByteProviderOptimizedSearchTests (17 tests)

Tests for ByteProvider optimized search methods using Span and ArrayPool.

Coverage:

• FindIndexOfOptimized() - Chunked search with ArrayPool
  • Multiple occurrences across file
  • Start position support
  • No-match handling
  • Small/large chunk sizes
  • Patterns at chunk boundaries
  • Edge cases (null, empty, beyond end)
• FindFirstOptimized() - Early-exit search
  • First occurrence finding
  • Start position support
  • No-match scenarios
• CountOccurrencesOptimized() - Optimized counting
  • Accurate counting
  • Start position support
  • Frequent patterns

Status: ✅ All 17 tests passing

🚀 Running Tests

All Tests

cd Sources/Tests/WpfHexEditor.Tests
dotnet test

Specific Test Class

dotnet test --filter "FullyQualifiedName~SpanSearchExtensionsTests"
dotnet test --filter "FullyQualifiedName~ByteProviderOptimizedSearchTests"

Single Test Method

dotnet test --filter "FullyQualifiedName~FindIndexOfOptimized_FindsAllOccurrences"

With Verbose Output

dotnet test --verbosity normal

Generate Code Coverage

dotnet test /p:CollectCoverage=true /p:CoverletOutputFormat=cobertura

🛠️ Requirements

• .NET 8.0 SDK for Windows
• Windows 10/11 (WPF dependency for ByteProvider tests)
• xUnit 2.6.6
• Microsoft.NET.Test.Sdk 17.8.0

Note: Tests target net8.0-windows with UseWPF=true because ByteProvider depends on PresentationFramework.

📝 Test Structure

Tests/
└── WpfHexEditor.Tests/
    ├── WpfHexEditor.Tests.csproj
    ├── SpanSearchExtensionsTests.cs       (Pure Span<byte> tests, no file I/O)
    ├── ByteProviderOptimizedSearchTests.cs (ByteProvider integration tests)
    └── README.md

🎯 Test Philosophy

Unit Tests (Current)

• Fast execution (< 2 seconds total)
• No external dependencies (temp files created/cleaned automatically)
• Deterministic (same input = same output)
• Isolated (each test independent)

Integration Tests (Future)

• Large file handling (GB-sized files)
• Performance regression detection
• Multi-threaded scenarios
• Memory profiling

📈 Test Results Example

Test Run Successful.
Total tests: 35
     Passed: 35
 Total time: 1.8423 Seconds

🧪 Adding New Tests

For Span Extensions

[Fact]
public void MyNewTest()
{
    // Arrange
    byte[] data = { /* test data */ };
    byte[] pattern = { /* search pattern */ };
    ReadOnlySpan<byte> span = new ReadOnlySpan<byte>(data);

    // Act
    var results = span.FindIndexOf(pattern, baseOffset: 0);

    // Assert
    Assert.Equal(expectedCount, results.Count);
    Assert.Equal(expectedPosition, results[0]);
}

For ByteProvider Tests

public class MyNewTests : IDisposable
{
    private readonly string _testFile;
    private readonly ByteProvider _provider;

    public MyNewTests()
    {
        _testFile = Path.GetTempFileName();
        // Create test data
        File.WriteAllBytes(_testFile, testData);
        _provider = new ByteProvider(_testFile);
    }

    public void Dispose()
    {
        _provider?.Dispose();
        if (File.Exists(_testFile))
            try { File.Delete(_testFile); } catch { }
    }

    [Fact]
    public void MyTest()
    {
        // Test using _provider
    }
}

🐛 Troubleshooting

Tests Fail with “Could not load PresentationFramework”

Solution: Ensure project targets net8.0-windows with <UseWPF>true</UseWPF>

Tests Fail with File Access Errors

Solution: Check that test cleanup (Dispose) is working correctly

Slow Test Execution

Solution:

• Reduce test file sizes if possible
• Use smaller chunk sizes for ByteProvider tests
• Run specific test classes instead of all tests

🔗 Related

• Benchmarks - Performance benchmarking with BenchmarkDotNet
• Performance Sample - Interactive performance demo
• Performance Extensions - API documentation

📜 License

Apache 2.0 - Same as WPF HexEditor parent project

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✅ All tests green!