Add comprehensive unit tests project for LogExpert.Core

[Copilot]

This PR adds a new unit tests project LogExpert.Core.UnitTests to provide test coverage for classes in the LogExpert.Core project, addressing issue requirements for better test coverage of core functionality.

What's Added

New Test Project

• LogExpert.Core.UnitTests targeting .NET 8.0 for cross-platform compatibility
• Uses NUnit testing framework with Moq for mocking, consistent with existing test projects
• Properly integrated into the solution and organized in the Tests folder structure

Comprehensive Test Coverage (140 tests)

The new test suite covers major LogExpert.Core components:

• Extensions: Tests for IEnumerable extension methods (IsEmpty)
• Utility Classes: File path handling, string validation, distance algorithms, and assertions
• Configuration Objects: Tool entries with property validation, cloning, and serialization behavior
• Data Entities: Range and EncodingOptions classes with property validation
• DateTimeParser Components: Section structures, token validation, and format string parsing
• Parameter Processing: Template parameter replacement with proper mocking for log line dependencies

Technical Implementation

Project Configuration

<TargetFramework>net8.0</TargetFramework>
<IsTestProject>true</IsTestProject>

The project targets net8.0 (not net8.0-windows) to ensure compatibility with Linux CI environments, following the pattern of ColumnizerLib.UnitTests rather than the Windows-dependent test projects.

Test Quality

• All tests follow AAA (Arrange-Act-Assert) pattern with descriptive names
• Proper edge case handling and null safety validation
• Uses Moq for mocking external dependencies like ILogLine
• Tests validate actual behavior including documented quirks (e.g., StripExtension behavior when no extension present)

Integration

• Added to solution file with proper folder organization
• Compatible with existing CI/CD pipeline
• No breaking changes to existing functionality
• All 140 new tests pass alongside existing test suites

Example Test Coverage

[TestCase("hello", "world", 4)]
[TestCase("kitten", "sitting", 3)]
public void DamerauLevenshteinDistance_VariousStrings_ReturnsCorrectDistance(string source, string destination, int expected)
{
    var result = Util.DamerauLevenshteinDistance(source, destination);
    Assert.That(result, Is.EqualTo(expected));
}

This establishes a solid foundation for testing LogExpert.Core functionality and provides a template for future test additions to maintain code quality and reliability.

Original prompt

Add A UnitTests Project for the Classes in the Project #LogExpert.Core

---

💬 Share your feedback on Copilot coding agent for the chance to win a $200 gift card! Click here to start the survey.