Add unit tests for command modules and utils

[Luladjiev]

No description provided.

[Copilot]

Pull Request Overview

This pull request adds comprehensive unit tests for command modules and utilities in the lgit Git wrapper tool. The PR adds test coverage for core functionality including command execution, CLI parsing, utility functions, and specific Git operations.

• Adds unit tests for the Cmd struct's exec method to validate Git command execution behavior
• Implements mock-based tests for command modules (rebase, fixup, checkout, cherry-pick, git fallback)
• Adds comprehensive CLI argument parsing tests for all command variants and flags

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/utils.rs	Adds tests for stash/unstash functionality and utility functions
src/commands/rebase.rs	Adds comprehensive tests for rebase operation with various failure scenarios
src/commands/git_fallback.rs	Adds tests for external Git command fallback functionality
src/commands/fixup.rs	Adds tests for commit log parsing and SHA extraction logic
src/commands/cherry_pick.rs	Adds tests for commit retrieval and parsing from branches
src/commands/checkout.rs	Adds tests for branch checkout operations and error handling
src/commands.rs	Adds integration tests for the real Git command execution
src/cli.rs	Adds comprehensive CLI argument parsing tests for all commands and aliases

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