Daily Test Coverage Improver - Add comprehensive tests for Matrix Range-based GetSlice

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Summary

This PR adds 15 comprehensive tests for the Matrix Range-based GetSlice functionality (mat.[r1..r2, c1..c2] syntax), providing thorough validation of this important user-facing API.

Changes Made

File Modified: tests/FsMath.Tests/MatrixCoverageGapsTests.fs

Tests Added: 15 new test cases in MatrixRangeGetSliceTests module

Test Coverage

The new tests validate:

• Full range extraction (mat.[0.., 0..])
• Explicit start and end indices (mat.[1..2, 1..2])
• From-start ranges (mat.[..1, ..2])
• To-end ranges (mat.[1.., 1..])
• Single row/column extraction (mat.[1..1, 0..], mat.[0.., 1..1])
• Mixed range operators (mat.[..2, 1..])
• Edge cases: First/last rows and columns
• Tall and wide matrices with various slice combinations
• Single element extraction as 1×1 matrix
• Corner submatrices (top-left, top-right, bottom-left, bottom-right)

Test Results

✅ All 1501 tests pass (8 skipped, 0 failed)
✅ Build succeeds with no new warnings or errors
✅ Functionality validated across diverse matrix sizes and range combinations

Test Coverage Results

Metric	Before	After	Change
Overall Coverage	78.74% (1630/2070)	78.74% (1630/2070)	+0.00%
Tests Passing	1486	1501	+15

Important Note on Coverage Metrics

The coverage percentage did not increase because the GetSlice(Range, Range) method (lines 132-141 in Matrix.fs) is an inline function, and F# coverage tools cannot track inline function execution.

However, this does NOT mean the tests are ineffective:

• ✅ All 15 new tests execute successfully and validate correct behavior
• ✅ The Range-based slice syntax is now comprehensively tested
• ✅ Edge cases, various matrix shapes, and range combinations are validated
• ✅ The inline function internally calls the non-inline GetSlice(int option, int option, int option, int option), which is tested

This is a known limitation mentioned by maintainers in Discussion #5:

"Since F# 8.0 it should be possible to cover inline functions by using quotation evaluation to dynamically invoke them."

The Range-based GetSlice cannot use the quotation technique because:

1. It's a member method (not a static inline function)
2. The Range type is not compatible with quotation evaluation

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-range-getslice-20251023-a1a45005

# 2. Build the project
./build.sh

# 3. Run tests to verify all pass
dotnet test tests/FsMath.Tests/FsMath.Tests.fsproj

# Expected output: Passed! - Failed: 0, Passed: 1501, Skipped: 8

# 4. Generate coverage report
dotnet test tests/FsMath.Tests/FsMath.Tests.fsproj \
  --collect:"XPlat Code Coverage" \
  --results-directory ./coverage \
  -- DataCollectionRunSettings.DataCollectors.DataCollector.Configuration.Format=cobertura

# 5. View coverage summary
find ./coverage -name "coverage.cobertura.xml" -exec python3 -c "
import xml.etree.ElementTree as ET
import sys
tree = ET.parse(sys.argv[1])
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)')
" {} \;

Areas for Future Work

Based on coverage analysis, remaining gaps in Matrix.fs include:

1. transposeByBlock (lines 156-174): Private inline function - cannot be tracked by coverage
2. multiplyRowVector SIMD paths (lines 610-636): Need specific test cases that trigger SIMD acceleration
3. muliplyVector SIMD loop (line 496): Needs tests with specific vector sizes
4. addColVector SIMD paths (lines 534, 572): Need appropriate matrix/vector combinations

These would benefit from:

• Targeted tests for SIMD code paths with specific dimensions
• Tests using different numeric types (float32, int, etc.)
• Potential quotation-based testing for static inline functions

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)

---

Bash Commands Used

# Branch creation
git checkout -b daily-test-improver-matrix-range-getslice-20251023-a1a45005

# Development
# (edited MatrixCoverageGapsTests.fs - added MatrixRangeGetSliceTests module)

# Build and test
./build.sh
dotnet test tests/FsMath.Tests/FsMath.Tests.fsproj

# Coverage collection
dotnet test tests/FsMath.Tests/FsMath.Tests.fsproj \
  --collect:"XPlat Code Coverage" \
  --results-directory ./coverage-new \
  -- DataCollectionRunSettings.DataCollectors.DataCollector.Configuration.Format=cobertura

# Coverage analysis
python3 -c "import xml.etree.ElementTree as ET; ..."

# Commit
git add tests/FsMath.Tests/MatrixCoverageGapsTests.fs
git commit -m "Add comprehensive tests for Matrix Range-based GetSlice syntax..."

Web Searches Performed

None - this work was based on:

• Existing test patterns in MatrixCoverageGapsTests.fs
• The Matrix.fs source code (lines 128-141)
• Understanding of F# Range syntax and indexing
• 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

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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 2025-10-28 at 12:08:49 UTC