Terminal.Gui/CONTRIBUTING.md

Contributing to Terminal.Gui

📘 This document is the single source of truth for all contributors (humans and AI agents) to Terminal.Gui.

Welcome! This guide provides everything you need to know to contribute effectively to Terminal.Gui, including project structure, build instructions, coding conventions, testing requirements, and CI/CD workflows.

Table of Contents

• Project Overview
• Key Architecture Concepts
• Coding Conventions
• Building and Testing
• Testing Requirements
• API Documentation Requirements
• Pull Request Guidelines
• CI/CD Workflows
• Repository Structure
• Branching Model
• What NOT to Do

Project Overview

Terminal.Gui is a cross-platform UI toolkit for creating console-based graphical user interfaces in .NET. It's a large codebase (~1,050 C# files) providing a comprehensive framework for building interactive console applications with support for keyboard and mouse input, customizable views, and a robust event system.

Key characteristics:

• Language: C# (net8.0)
• Platform: Cross-platform (Windows, macOS, Linux)
• Architecture: Console UI toolkit with driver-based architecture
• Version: v2 (Alpha), v1 (maintenance mode)
• Branching: GitFlow model (v2_develop is default/active development)

Key Architecture Concepts

⚠️ CRITICAL - AI Agents MUST understand these concepts before starting work.

• Application Lifecycle - How Application.Init, Application.Run, and Application.Shutdown work - Application Deep Dive
• Cancellable Workflow Patern - CWP Deep Dive
• View Hierarchy - Understanding View, Runnable, Window, and view containment - View Deep Dive
• Layout System - Pos, Dim, and automatic layout - Layout System
• Event System - How keyboard, mouse, and application events flow - Events Deep Dive
• Driver Architecture - How console drivers abstract platform differences - Drivers
• Drawing Model - How rendering works with Attributes, Colors, and Glyphs - Drawing Deep Dive

Building and Testing

Required Tools

• .NET SDK: 8.0.0 (see global.json)
• Runtime: .NET 8.x (latest GA)
• Optional: ReSharper/Rider for code formatting (honor .editorconfig and Terminal.sln.DotSettings)

Build Commands (In Order)

ALWAYS run these commands from the repository root:

1. Restore packages (required first, ~15-20 seconds):

   dotnet restore
   

2. Build solution (Debug, ~50 seconds):

   dotnet build --configuration Debug --no-restore
   

   • Expect ~326 warnings (nullable reference warnings, unused variables, etc.) - these are normal
   • 0 errors expected

3. Build Release (for packaging):

   dotnet build --configuration Release --no-restore
   

Test Commands

Two test projects exist:

1. Non-parallel tests (depend on static state, ~10 min timeout):

   dotnet test Tests/UnitTests --no-build --verbosity normal
   

   • Uses Application.Init and static state
   • Cannot run in parallel
   • Includes --blame flags for crash diagnostics

2. Parallel tests (can run concurrently, ~10 min timeout):

   dotnet test Tests/UnitTestsParallelizable --no-build --verbosity normal
   

   • No dependencies on static state
   • Preferred for new tests

3. Integration tests:

   dotnet test Tests/IntegrationTests --no-build --verbosity normal
   

Common Build Issues

Issue: NativeAot/SelfContained Build

• Solution: Restore these projects explicitly:

  dotnet restore ./Examples/NativeAot/NativeAot.csproj -f
  dotnet restore ./Examples/SelfContained/SelfContained.csproj -f
  

Coding Conventions

⚠️ CRITICAL - These rules MUST be followed in ALL new or modified code

Code Style Tenets

1. Six-Year-Old Reading Level - Readability over terseness
2. Consistency, Consistency, Consistency - Follow existing patterns ruthlessly
3. Don't be Weird - Follow Microsoft/.NET conventions
4. Set and Forget - Rely on automated tooling
5. Documentation is the Spec - API docs are source of truth

Code Formatting

⚠️ CRITICAL - These rules MUST be followed in ALL new or modified code:

• Do NOT add formatting tools - Use existing .editorconfig and Terminal.sln.DotSettings

• Format code with:

  1. ReSharper/Rider (Ctrl-E-C)
  2. JetBrains CleanupCode CLI tool (free)
  3. Visual Studio (Ctrl-K-D) as fallback

• Only format files you modify

• Follow .editorconfig settings (e.g., braces on new lines, spaces after keywords)

• 4-space indentation

• No trailing whitespace

• File-scoped namespaces

• ALWAYS use explicit types - Never use var except for built-in simple types (int, string, bool, double, float, decimal, char, byte)

  // ✅ CORRECT - Explicit types
  View view = new () { Width = 10 };
  MouseEventArgs args = new () { Position = new Point(5, 5) };
  List<View?> views = new ();
  var count = 0;  // OK - int is a built-in type
  var name = "test";  // OK - string is a built-in type
  
  // ❌ WRONG - Using var for non-built-in types
  var view = new View { Width = 10 };
  var args = new MouseEventArgs { Position = new Point(5, 5) };
  var views = new List<View?>();
  

• ALWAYS use target-typed new () - Use new () instead of new TypeName() when the type is already declared

  // ✅ CORRECT - Target-typed new
  View view = new () { Width = 10 };
  MouseEventArgs args = new ();
  
  // ❌ WRONG - Redundant type name
  View view = new View() { Width = 10 };
  MouseEventArgs args = new MouseEventArgs();
  

⚠️ CRITICAL - These conventions apply to ALL code - production code, test code, examples, and samples.

Testing Requirements

Code Coverage

• Never decrease code coverage - PRs must maintain or increase coverage
• Target: 70%+ coverage for new code
• Coverage collection:
• Centralized in TestResults/ directory at repository root
• Collected only on Linux (ubuntu-latest) runners in CI for performance
• Windows and macOS runners skip coverage collection to reduce execution time
• Coverage reports uploaded to Codecov automatically from Linux runner
• CI monitors coverage on each PR

Test Patterns

• Make tests granular - Each test should cover smallest area possible
• Follow existing test patterns in respective test projects
• Avoid adding new tests to the UnitTests Project - Make them parallelizable and add them to UnitTests.Parallelizable
• Avoid static dependencies - DO NOT use the legacy/static Application API or ConfigurationManager in tests unless the tests explicitly test related functionality.
• Don't use [AutoInitShutdown] or [SetupFakeApplication] - Legacy pattern, being phased out

Test Configuration

• xunit.runner.json - xUnit configuration
• coverlet.runsettings - Coverage settings (OpenCover format)

API Documentation Requirements

All public APIs MUST have XML documentation:

• Clear, concise <summary> tags
• Use <see cref=""/> for cross-references
• Add <remarks> for context
• Include <example> for non-obvious usage
• Complex topics → docfx/docs/*.md files
• Proper English and grammar - Clear, concise, complete. Use imperative mood.

Pull Request Guidelines

PR Requirements

• ALWAYS include instructions for pulling down locally at end of Description

• Title: "Fixes #issue. Terse description". If multiple issues, list all, separated by commas (e.g. "Fixes #123, #456. Terse description")

• Description:

  • Include "- Fixes #issue" for each issue near the top
  • Suggest user setup a remote named copilot pointing to your fork
  • Example:

    # To pull down this PR locally:
    git remote add copilot <your-fork-url>
    git fetch copilot <branch-name>
    git checkout copilot/<branch-name>
    

• Tests: Add tests for new functionality (see Testing Requirements)

• Coverage: Maintain or increase code coverage

• Scenarios: Update UICatalog scenarios when adding features

• Warnings: CRITICAL - PRs must not introduce any new warnings

  • Any file modified in a PR that currently generates warnings MUST be fixed to remove those warnings
  • Exception: Warnings caused by [Obsolete] attributes can remain
  • Action: Before submitting a PR, verify your changes don't add new warnings and fix any warnings in files you modify

Repository Structure

Root Directory Files

• Terminal.sln - Main solution file
• Terminal.sln.DotSettings - ReSharper code style settings
• .editorconfig - Code formatting rules (111KB, extensive)
• global.json - .NET SDK version pinning
• Directory.Build.props - Common MSBuild properties
• Directory.Packages.props - Central package version management
• GitVersion.yml - Version numbering configuration
• CONTRIBUTING.md - This file - contribution guidelines (source of truth)
• AGENTS.md - Pointer to this file for AI agents
• README.md - Project documentation

Main Directories

/Terminal.Gui/ - Core library (496 C# files):

• App/ - Application lifecycle (Application.cs static class, SessionToken, MainLoop)
• Configuration/ - ConfigurationManager for settings
• Drivers/ - Console driver implementations (Dotnet, Windows, Unix, Fake)
• Drawing/ - Rendering system (attributes, colors, glyphs)
• Input/ - Keyboard and mouse input handling
• ViewBase/ - Core View class hierarchy and layout
• Views/ - Specific View subclasses (Window, Dialog, Button, ListView, etc.)
• Text/ - Text manipulation and formatting
• FileServices/ - File operations and services

/Tests/:

• UnitTests/ - Non-parallel tests (use Application.Init, static state)
• UnitTestsParallelizable/ - Parallel tests (no static dependencies) - Preferred
• IntegrationTests/ - Integration tests
• StressTests/ - Long-running stress tests (scheduled daily)
• coverlet.runsettings - Code coverage configuration

/Examples/:

• UICatalog/ - Comprehensive demo app for manual testing
• Example/ - Basic example
• NativeAot/, SelfContained/ - Deployment examples
• ReactiveExample/, CommunityToolkitExample/ - Integration examples

/docfx/ - Documentation source:

• docs/ - Conceptual documentation (deep dives)
• api/ - Generated API docs (gitignored)
• docfx.json - DocFX configuration

/Scripts/ - PowerShell build utilities (requires PowerShell 7.4+)

/.github/workflows/ - CI/CD pipelines (see CI/CD Workflows)

Branching Model

GitFlow Model

• v2_develop - Default branch, active development
• v2_release - Stable releases, matches NuGet
• v1_develop, v1_release - Legacy v1 (maintenance only)

What NOT to Do

• ❌ Don't add new linters/formatters (use existing)
• ❌ Don't modify unrelated code
• ❌ Don't remove/edit unrelated tests
• ❌ Don't break existing functionality
• ❌ Don't add tests to UnitTests if they can be parallelizable
• ❌ Don't use Application.Init in new tests
• ❌ Don't decrease code coverage
• ❌ Don't use var for anything but built-in simple types (use explicit types)
• ❌ Don't use redundant type names with new (ALWAYS PREFER target-typed new ())
• ❌ Don't introduce new warnings (fix warnings in files you modify; exception: [Obsolete] warnings)

Thank you for contributing to Terminal.Gui! 🎉