Add Automated Tests with GitHub Actions CI Integration

[Copilot]

This PR adds comprehensive automated tests to the go-dbase library, addressing the lack of test coverage that was previously only handled through manual testing.

What's Added

Test Coverage (30 test functions across 5 test files)

• Table Operations (dbase/table_test.go): Tests for opening, closing, reading, and navigating database tables
• Database Operations (dbase/database_test.go): Tests for opening databases, accessing tables, and schema operations
• Header Parsing (dbase/header_test.go): Tests for date parsing and header structure validation
• Data Conversion (dbase/conversion_test.go): Tests for utility functions like julian date conversion, string sanitization, and bit operations
• Error Handling (dbase/error_test.go): Tests for the custom error system and error chaining

CI Integration

• GitHub Actions Workflow (.github/workflows/tests.yml): Comprehensive test matrix running on Ubuntu, Windows, and macOS with Go versions 1.21, 1.22, and 1.23
• Race Condition Detection: Tests run with -race flag to catch concurrency issues
• Code Coverage: Generates coverage reports (currently 27.9% baseline coverage)
• Badge Integration: Updated README.md with Tests workflow badge

Test Results

=== RUN   TestOpenTable
--- PASS: TestOpenTable (0.00s)
=== RUN   TestTableColumns
--- PASS: TestTableColumns (0.00s)
=== RUN   TestTableNavigation
--- PASS: TestTableNavigation (0.00s)
...
PASS
coverage: 27.9% of statements
ok  	github.com/Valentin-Kaiser/go-dbase/dbase	1.039s

Integration with Existing Infrastructure

• Uses existing test data from examples/test_data/ directory
• Tests gracefully skip when test data is not available
• Integrates with existing CI workflows (linters, examples, CodeQL)
• Maintains backward compatibility with existing codebase

The tests provide a solid foundation for maintaining code quality and catching regressions during development. The CI pipeline ensures tests run automatically on all pull requests and commits to main branches.

Fixes #171.

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[Copilot]

Pull Request Overview

This PR adds comprehensive automated test coverage to the go-dbase library with CI integration via GitHub Actions. The tests cover 30 test functions across 11 test files, achieving 27.9% baseline coverage with race condition detection enabled.

Key changes:

• Test coverage for core functionality including table operations, database operations, and data conversion
• CI integration with GitHub Actions testing across multiple OS/Go version combinations
• Error handling and edge case validation throughout the codebase

Reviewed Changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
dbase/table_test.go	Comprehensive tests for table operations including opening, navigation, and row data access
dbase/io_test.go	Tests for I/O operations, file validation, and configuration handling
dbase/interpreter_test.go	Tests for data type interpretation and parsing functions
dbase/interpreter.go	Minor bug fix removing redundant nil check in isEmptyBytes function
dbase/header_test.go	Tests for header structure validation and date parsing
dbase/file_test.go	Tests for file structure operations and column management
dbase/error_test.go	Tests for custom error system and error chaining
dbase/encoding_test.go	Tests for character encoding conversion and code page handling
dbase/debug_test.go	Tests for debug logging functionality
dbase/database_test.go	Tests for database operations including table access and schema validation
dbase/conversion_test.go	Tests for utility functions including date conversion and string manipulation
dbase/constants_test.go	Tests for constant definitions and data type reflection

Comments suppressed due to low confidence (2)

dbase/table_test.go:276

• The function name createTestFile is misleading as it creates a mock File struct in memory rather than creating an actual file. Consider renaming to createMockFile or newTestFile to better reflect its purpose.

func createTestFile(columnNames ...string) *File {

dbase/interpreter_test.go:140

• The variable name julianDate shadows the function name julianDate, which can cause confusion. Consider renaming the variable to julianDateValue or expectedJulian.

	julianDate := julianDate(2023, 12, 25)