Polyglot Test Generation Skill

An AI-powered skill that generates comprehensive, workable unit tests for any programming language using a coordinated multi-agent pipeline.

When to Use This Skill

Use this skill when you need to:

• Generate unit tests for an entire project or specific files
• Improve test coverage for existing codebases
• Create test files that follow project conventions
• Write tests that actually compile and pass
• Add tests for new features or untested code

How It Works

This skill coordinates multiple specialized agents in a Research → Plan → Implement pipeline:

Pipeline Overview

┌─────────────────────────────────────────────────────────────┐
│                     TEST GENERATOR                          │
│  Coordinates the full pipeline and manages state            │
└─────────────────────┬───────────────────────────────────────┘
                      │
        ┌─────────────┼─────────────┐
        ▼             ▼             ▼
┌───────────┐  ┌───────────┐  ┌───────────────┐
│ RESEARCHER│  │  PLANNER  │  │  IMPLEMENTER  │
│           │  │           │  │               │
│ Analyzes  │  │ Creates   │  │ Writes tests  │
│ codebase  │→ │ phased    │→ │ per phase     │
│           │  │ plan      │  │               │
└───────────┘  └───────────┘  └───────┬───────┘
                                      │
                    ┌─────────┬───────┼───────────┐
                    ▼         ▼       ▼           ▼
              ┌─────────┐ ┌───────┐ ┌───────┐ ┌───────┐
              │ BUILDER │ │TESTER │ │ FIXER │ │LINTER │
              │         │ │       │ │       │ │       │
              │ Compiles│ │ Runs  │ │ Fixes │ │Formats│
              │ code    │ │ tests │ │ errors│ │ code  │
              └─────────┘ └───────┘ └───────┘ └───────┘

Step-by-Step Instructions

Step 1: Determine the User Request

Make sure you understand what user is asking and for what scope. When the user does not express strong requirements for test style, coverage goals, or conventions, source the guidelines from unit-test-generation.prompt.md. This prompt provides best practices for discovering conventions, parameterization strategies, coverage goals (aim for 80%), and language-specific patterns.

Step 2: Invoke the Test Generator

Start by calling the polyglot-test-generator agent with your test generation request:

Generate unit tests for [path or description of what to test], following the [unit-test-generation.prompt.md](unit-test-generation.prompt.md) guidelines

The Test Generator will manage the entire pipeline automatically.

Step 3: Research Phase (Automatic)

The polyglot-test-researcher agent analyzes your codebase to understand:

• Language & Framework: Detects C#, TypeScript, Python, Go, Rust, Java, etc.
• Testing Framework: Identifies MSTest, xUnit, Jest, pytest, go test, etc.
• Project Structure: Maps source files, existing tests, and dependencies
• Build Commands: Discovers how to build and test the project

Output: .testagent/research.md

Step 4: Planning Phase (Automatic)

The polyglot-test-planner agent creates a structured implementation plan:

• Groups files into logical phases (2-5 phases typical)
• Prioritizes by complexity and dependencies
• Specifies test cases for each file
• Defines success criteria per phase

Output: .testagent/plan.md

Step 5: Implementation Phase (Automatic)

The polyglot-test-implementer agent executes each phase sequentially:

1. Read source files to understand the API
2. Write test files following project patterns
3. Build using the polyglot-test-builder subagent to verify compilation
4. Test using the polyglot-test-tester subagent to verify tests pass
5. Fix using the polyglot-test-fixer subagent if errors occur
6. Lint using the polyglot-test-linter subagent for code formatting

Each phase completes before the next begins, ensuring incremental progress.

Coverage Types

• Happy path: Valid inputs produce expected outputs
• Edge cases: Empty values, boundaries, special characters
• Error cases: Invalid inputs, null handling, exceptions

State Management

All pipeline state is stored in .testagent/ folder:

File	Purpose
.testagent/research.md	Codebase analysis results
.testagent/plan.md	Phased implementation plan
.testagent/status.md	Progress tracking (optional)

Examples

Example 1: Full Project Testing

Generate unit tests for my Calculator project at C:\src\Calculator

Example 2: Specific File Testing

Generate unit tests for src/services/UserService.ts

Example 3: Targeted Coverage

Add tests for the authentication module with focus on edge cases

Agent Reference

Agent	Purpose	Tools
polyglot-test-generator	Coordinates pipeline	runCommands, codebase, editFiles, search, runSubagent
polyglot-test-researcher	Analyzes codebase	runCommands, codebase, editFiles, search, fetch, runSubagent
polyglot-test-planner	Creates test plan	codebase, editFiles, search, runSubagent
polyglot-test-implementer	Writes test files	runCommands, codebase, editFiles, search, runSubagent
polyglot-test-builder	Compiles code	runCommands, codebase, search
polyglot-test-tester	Runs tests	runCommands, codebase, search
polyglot-test-fixer	Fixes errors	runCommands, codebase, editFiles, search
polyglot-test-linter	Formats code	runCommands, codebase, search

Requirements

• Project must have a build/test system configured
• Testing framework should be installed (or installable)
• VS Code with GitHub Copilot extension

Troubleshooting

Tests don't compile

The polyglot-test-fixer agent will attempt to resolve compilation errors. Check .testagent/plan.md for the expected test structure.

Tests fail

Review the test output and adjust test expectations. Some tests may require mocking dependencies.

Wrong testing framework detected

Specify your preferred framework in the initial request: "Generate Jest tests for..."