Daily Test Coverage Improver - Comprehensive SIMD Tests for Matrix Vector Operations

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Summary

This PR adds 23 comprehensive tests specifically targeting SIMD-optimized code paths in Matrix vector operations: muliplyVector, addRowVector, and addColVector. These tests thoroughly validate SIMD implementation, edge cases, and mathematical correctness.

Changes Made

New File Created: tests/FsMath.Tests/MatrixSIMDCoverageTests.fs

Tests Added: 23 new test cases specifically designed to execute SIMD paths

Test Coverage

The new tests target three critical functions and their SIMD paths:

1. Matrix.muliplyVector (line 496: SIMD accumulation loop)

• 8 tests covering various matrix sizes and data types
• Tests with 4, 5, 8, 12, 16 columns to trigger different SIMD scenarios
• Validates identity matrix, zero matrix, and numerical correctness
• Tests both float and float32 types

2. Matrix.addRowVector (line 534: SIMD addition loop)

• 8 tests covering SIMD row-vector addition
• Tests with 4, 5, 8, 9, 12, 16 columns
• Validates negative values and large matrices
• Tests both SIMD chunks and scalar tail processing

3. Matrix.addColVector (line 572: SIMD broadcast addition)

• 7 tests covering SIMD column-vector addition
• Tests with 4, 5, 8, 12, 16, 20 columns
• Validates broadcast mechanism and scalar tail handling
• Extensive validation across different matrix shapes

Test Results

✅ All 1509 tests pass (up from 1486, +23 new tests)
✅ Build succeeds with no new warnings or errors
✅ Functionality validated across diverse matrix configurations and SIMD scenarios

Test Coverage Results

Metric	Before	After	Change
Overall Coverage	78.74% (1630/2070)	78.74% (1630/2070)	+0.00%
Tests Passing	1486	1509	+23

Important Note on Coverage Metrics

The coverage percentage did not increase because all three functions (muliplyVector, addRowVector, addColVector) are marked as inline functions, and F# coverage tools cannot track inline function execution. Lines 496, 534, and 572 are within these inline functions.

However, this does NOT mean the tests are ineffective:

• ✅ All 23 new tests execute successfully and validate correct behavior
• ✅ The SIMD paths are now comprehensively tested with matrices large enough to trigger SIMD
• ✅ Edge cases, various matrix shapes, and both SIMD and scalar tail paths are validated
• ✅ Mathematical correctness is verified across all scenarios
• ✅ The tests would catch any regressions if the implementation changes

This is a known limitation mentioned by maintainers in Discussion #5 and documented in previous test coverage work.

Replicating the Test Coverage Measurements

To replicate these tests and coverage:

# 1. Check out this branch
git fetch origin
git checkout daily-test-improver-matrix-simd-gaps-20251028-9261f48d768e4876

# 2. Build the project
dotnet build --no-restore

# 3. Run tests to verify all pass
dotnet test tests/FsMath.Tests/FsMath.Tests.fsproj --no-build

# Expected output: Passed! - Failed: 0, Passed: 1509, Skipped: 8

# 4. Run only the new SIMD tests
dotnet test tests/FsMath.Tests/FsMath.Tests.fsproj --no-build \
  --filter "FullyQualifiedName~MatrixSIMDCoverageTests"

# Expected output: Passed! - Failed: 0, Passed: 23, Skipped: 0

# 5. Generate coverage report
dotnet test tests/FsMath.Tests/FsMath.Tests.fsproj \
  --no-build \
  --collect:"XPlat Code Coverage" \
  --results-directory ./coverage \
  -- DataCollectionRunSettings.DataCollectors.DataCollector.Configuration.Format=cobertura

# 6. View coverage summary (will show 78.74% due to inline limitation)
python3 << 'PYEOF'
import xml.etree.ElementTree as ET
import glob
coverage_file = glob.glob('./coverage/*/coverage.cobertura.xml')[0]
tree = ET.parse(coverage_file)
root = tree.getroot()
rate = float(root.get('line-rate'))
covered = root.get('lines-covered')
valid = root.get('lines-valid')
print(f'Coverage: {rate*100:.2f}% ({covered}/{valid} lines)')
PYEOF

Test Design Strategy

The tests were carefully designed to ensure SIMD code paths execute:

SIMD Activation Requirements

• Vector<float>.Count is typically 4 on most systems
• Vector<float32>.Count is typically 8
• Matrix columns must be >= SIMD width for SIMD to activate

Test Categories

1. Exact SIMD fit (4 columns for float, 8 for float32): Tests matrices where column count exactly matches SIMD width
2. Multiple SIMD chunks (8, 12, 16 columns): Tests with multiple full SIMD iterations
3. SIMD + scalar tail (5, 6, 9 columns): Tests mixed SIMD and scalar processing
4. Large matrices (20+ columns): Stress tests for extensive SIMD processing
5. Type variations: Tests with both float and float32 to validate generic implementation
6. Edge cases: Identity matrices, zero matrices, negative values

Mathematical Validation

Each test verifies:

• Correct SIMD accumulation/addition
• Proper handling of scalar tail elements
• Mathematical correctness of results
• Edge case behavior (zeros, negatives, identity)

Areas for Future Work

Based on the current state of Matrix.fs coverage, remaining inline function gaps include:

1. multiplyRowVector (lines 610-636): Already addressed in PR Daily Test Coverage Improver - Comprehensive SIMD Tests for Matrix.multiplyRowVector #84
2. SpanPrimitives.fs (0%): Inline Span functions (cannot use quotation technique due to Span/byref types)
3. SpanMath.fs (0%): Inline span-based math operations
4. SIMDUtils.fs (0%): Inline SIMD utility operations

For functions that can be tested with the quotation technique (as demonstrated in previous PRs for VectorModule, Householder, GenericMath, etc.), that approach can improve coverage metrics. However, for inline functions with Span/byref parameters or member methods, comprehensive functional testing (like this PR) is the best approach to ensure correctness.

Significance

These tests are important because:

1. Critical User-Facing APIs: muliplyVector, addRowVector, and addColVector are fundamental matrix operations
2. SIMD Optimization Testing: Validates that SIMD acceleration paths work correctly across various scenarios
3. Regression Prevention: Comprehensive test coverage prevents future regressions
4. Edge Case Coverage: Tests validate behavior under various matrix configurations and data types
5. Performance Path Validation: Ensures optimizations function correctly with both SIMD and scalar paths

The SIMD-optimized Matrix vector operations are now comprehensively tested, even if coverage metrics don't reflect it due to the inline function limitation.

Related Discussions

• Discussion #5: Daily Test Coverage Improver - Research and Plan
• Maintainer note on inline function coverage (Comment in Discussion Daily Test Coverage Improver - Research and Plan #5)
• Related PR Daily Test Coverage Improver - Comprehensive SIMD Tests for Matrix.multiplyRowVector #84: SIMD tests for Matrix.multiplyRowVector

---

Bash Commands Used

# Coverage analysis before
dotnet test tests/FsMath.Tests/FsMath.Tests.fsproj \
  --no-build \
  --collect:"XPlat Code Coverage" \
  --results-directory ./coverage \
  -- DataCollectionRunSettings.DataCollectors.DataCollector.Configuration.Format=cobertura

# Branch creation
git checkout -b daily-test-improver-matrix-simd-gaps-20251028-9261f48d768e4876

# Development
# Created MatrixSIMDCoverageTests.fs with 23 comprehensive tests
# Updated FsMath.Tests.fsproj to include new test file

# Build and test
dotnet build tests/FsMath.Tests/FsMath.Tests.fsproj --no-restore
dotnet test tests/FsMath.Tests/FsMath.Tests.fsproj --no-build --filter "FullyQualifiedName~MatrixSIMDCoverageTests"
dotnet test tests/FsMath.Tests/FsMath.Tests.fsproj --no-build

# Coverage after
dotnet test tests/FsMath.Tests/FsMath.Tests.fsproj \
  --no-build \
  --collect:"XPlat Code Coverage" \
  --results-directory ./coverage-new \
  -- DataCollectionRunSettings.DataCollectors.DataCollector.Configuration.Format=cobertura

# Coverage comparison
python3 # (coverage comparison script)

# Commit
git add tests/FsMath.Tests/MatrixSIMDCoverageTests.fs tests/FsMath.Tests/FsMath.Tests.fsproj
git commit -m "Add comprehensive SIMD tests for Matrix vector operations..."

Web Searches Performed

None - this work was based on:

• Code analysis of Matrix.fs (lines 468-578)
• Coverage report analysis showing uncovered lines 496, 534, 572
• Understanding of SIMD requirements (Vector.Count varies by type)
• Existing test patterns in the codebase
• Discussion Daily Test Coverage Improver - Research and Plan #5 about inline function coverage limitations

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🤖 Generated with Claude Code

AI generated by Daily Test Coverage Improver

AI generated by Daily Test Coverage Improver

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📊 Code Coverage Report

Summary

Package	Line Rate	Branch Rate	Complexity	Health
FsMath	78%	51%	4373	➖
FsMath	78%	51%	4373	➖
Summary	78% (3154 / 4038)	51% (4410 / 8610)	8746	➖

📈 Coverage Analysis

🟡 Good Coverage Your code coverage is above 60%. Consider adding more tests to reach 80%.

🎯 Coverage Goals

• Target: 80% line coverage
• Minimum: 60% line coverage
• Current: 78% line coverage

📋 What These Numbers Mean

• Line Rate: Percentage of code lines that were executed during tests
• Branch Rate: Percentage of code branches (if/else, switch cases) that were tested
• Health: Overall assessment combining line and branch coverage

🔗 Detailed Reports

📋 Download Full Coverage Report - Check the 'coverage-report' artifact for detailed HTML coverage report

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Coverage report generated on 2025-10-29 at 05:46:02 UTC