Agent365-devTools: Instructions file for GitHub Copilot

GitHub Copilot Instructions for Agent365-devTools

Agent365 CLI Development Guidelines

Engineering Principles

• Follow KISS, DRY, SOLID, and YAGNI principles
• Align CLI patterns with Azure CLI (az) conventions
• Keep changes minimal and focused on the problem at hand
• Reuse existing functions across commands; avoid duplication
• Critically review all changes before committing

Code Organization

• Keep files small and focused
• Use constants for strings and values (see Constants/ folder)
• Use ErrorCodes.cs and ErrorMessages.cs for error handling

File Organization Guidelines

Multiple Classes Per File - Allowed Cases

• Model/DTO files: Related model classes, records, or structs can be grouped in a single file
• Request/Response pairs: API request and response classes for the same endpoint
• Small supporting types: Enums, small records, or helper classes closely tied to a main class
• Nested or related interfaces: Interface and its related types

When to Separate

• Large classes with significant logic
• Classes that could be reused independently
• Classes with different lifecycle or ownership

Cross-Platform Compatibility

• All code must work on Windows, macOS, and Linux
• Test file paths, line endings, and shell commands for compatibility

Testing Standards

• Use xUnit, FluentAssertions, and NSubstitute
• Focus on quality over quantity of tests
• Add regression tests for bug fixes
• Tests should verify CLI reliability
• Tests must assert requirements, not implementation — when a test is changed to match new code behavior (rather than to reflect a changed requirement), that is a red flag. A test that silently tracks whatever the code does provides no regression protection. If a test needs to be updated, explicitly document the requirement the new assertion encodes (use because: in FluentAssertions). If you cannot articulate a requirement reason, the test change should be questioned.
• FluentAssertions because: is mandatory for non-obvious assertions — any assertion on a URL structure, encoding format, security-sensitive behavior, or protocol requirement must include a because: clause explaining the invariant being enforced.
• Dispose IDisposable objects properly:
  • HttpResponseMessage objects created in tests must be disposed
  • Even in mock/test handlers, follow proper disposal patterns
  • Consider using using statements or ensure test handlers dispose responses
  • This applies to all IDisposable test objects to avoid analyzer warnings
• Disable parallel execution for tests with shared state:
  • Tests that modify environment variables must disable parallelization
  • Tests that access shared file system resources must run sequentially
  • Use [CollectionDefinition("TestName", DisableParallelization = true)] pattern
  • Add [Collection("TestName")] attribute to test class
  • Pattern to follow:

    /// <summary>
    /// Tests must run sequentially because they modify environment variables.
    /// </summary>
    [CollectionDefinition("EnvTests", DisableParallelization = true)]
    public class EnvTestCollection { }
    
    [Collection("EnvTests")]
    public class MyTests
    {
        [Fact]
        public void Test_ModifiesEnvironmentVariable()
        {
            Environment.SetEnvironmentVariable("VAR", "value");
            try
            {
                // Test logic
            }
            finally
            {
                Environment.SetEnvironmentVariable("VAR", null);
            }
        }
    }