Daily Test Coverage Improver: Add comprehensive TorchExtensions tests

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Summary

This PR adds comprehensive test coverage for the TorchExtensions module, which provides essential tensor conversion utilities between Furnace and PyTorch. The module previously had 0% test coverage and is now at 75% line coverage.

Problems Found

1. Zero test coverage: The TorchExtensions module had no tests despite containing critical functionality for PyTorch integration
2. Untested conversion paths: Key tensor conversion methods (fromTorch, toTorch) were completely untested
3. Missing error handling verification: No tests verified proper exception handling for invalid backend conversions

Actions Taken

Added 7 comprehensive test methods covering:

Core Functionality Tests:

• TestTorchExtensionsFromTorchTensor() - Basic 1D tensor round-trip conversion
• TestTorchExtensionsFromTorchTensor2D() - 2D tensor conversion with shape preservation
• TestTorchExtensionsFromTorchScalar() - Scalar tensor conversion
• TestTorchExtensionsRoundTripLargerTensor() - 3D tensor conversion with random data

Data Type & Backend Tests:

• TestTorchExtensionsToTorchWithDifferentDtypes() - Float32, Float64, Int32 dtype preservation
• TestTorchExtensionsToTorchWithNonTorchBackend() - Exception handling for non-Torch tensors
• TestTorchExtensionsBoolTensorRoundTrip() - Boolean tensor conversion

Functions Covered:

• FurnaceImage.fromTorch(torch.Tensor) - Creates Furnace tensor from PyTorch tensor
• tensor.toTorch() - Converts Furnace tensor to PyTorch tensor (with backend validation)

Coverage Changes

Before:

• TorchExtensions module: 0.0% line coverage
• Total project coverage: 73.4%
• Torch backend: 83.38% line coverage
• Torch Utils: 58.5% line coverage

After:

• TorchExtensions module: 75.0% line coverage ⬆️ +75%
• Total project coverage: 73.7% ⬆️ +0.3%
• Torch backend: 84.22% line coverage ⬆️ +0.84%
• Torch Utils: 68.2% line coverage ⬆️ +9.7%

Test Design Features

• Comprehensive data types: Float32, Float64, Int32, Bool tensors
• Multiple tensor shapes: Scalars, 1D, 2D, 3D tensors
• Error handling: Verifies exception throwing for invalid backend conversions
• Value preservation: Ensures numerical accuracy with floating-point tolerance
• Shape preservation: Ensures tensor dimensions are maintained through conversions
• Backend compatibility: Tests both Torch and Reference backend interactions

Future Recommendations

Additional areas identified for potential coverage improvements:

1. MNIST module loading and processing (currently 0% coverage)
2. DataUtil module (currently 0% coverage, but addressed in PR Daily Test Coverage Improver: Add comprehensive DataUtil module tests #51)
3. Reference backend Utils module (challenging due to internal scope)
4. Branch coverage improvements for conditional logic paths

Validation Commands

To verify coverage improvements:

dotnet test --configuration Release /p:CollectCoverage=true /p:CoverletOutputFormat=opencover /p:CoverletOutput="coverage.opencover.xml"
dotnet tool install -g dotnet-reportgenerator-globaltool
reportgenerator -reports:"coverage.opencover.xml" -targetdir:"coverage" -reporttypes:"Html;TextSummary"

Commands Executed

Bash Commands:

• dotnet --version - Check .NET version
• dotnet restore - Install dependencies
• dotnet build --configuration Release --no-restore --verbosity normal - Build project
• dotnet test tests/Furnace.Tests --configuration Release --no-build --filter TestTorchExtensions - Run specific tests
• dotnet test tests/Furnace.Tests --configuration Release --no-build /p:CollectCoverage=true /p:CoverletOutputFormat=opencover /p:CoverletOutput="coverage.opencover.xml" --logger trx - Full coverage analysis
• reportgenerator -reports:"coverage.opencover.xml" -targetdir:"coverage" -reporttypes:"Html;TextSummary;Badges" - Generate coverage reports
• dotnet format - Apply code formatting

MCP Function/Tool Calls:

• mcp__github__search_issues - Found existing research issue Daily Test Coverage Improver: Research and Plan #46
• mcp__github__get_issue_comments - Read previous work comments
• mcp__github__search_pull_requests - Checked for existing Daily Test Coverage Improver PRs
• Read - Analyzed TorchExtensions source code structure
• Write - Created TestTorchExtensions.fs test file
• Edit - Updated project file and fixed test compilation issues
• Grep - Searched codebase for patterns and existing test structures

AI-generated content by Daily Test Coverage Improver may contain mistakes.