# 🧪 Testgen Guide

The `testgen` command generates high-quality unit tests for your existing code files using AI. It's designed to match your project's testing conventions and use the most modern practices for each language.

### Benefits

- **Go**: Table-driven `t.Parallel()` matching codebase.
- **Python**: Pytest with `@parametrize`.
- **C**: Check framework suites.
- **C++**: Google Test `EXPECT_*`.
- **Boosts coverage**; safe preview.

### Usage

Generate comprehensive unit tests for Go/Python/C/C++ files using AI.

```bash
grokkit testgen internal/grok/client.go
grokkit testgen app.py --yes
grokkit testgen foo.c bar.cpp
```

### Safety Features

- **Lang detection** via `internal/linter`.
- **Unified diff preview**.
- **Y/N confirmation** (`--yes` to auto-confirm).

### Options

| Flag | Description |
|------|-------------|
| `--yes`, `-y` | Skip the confirmation prompt and write tests immediately |
| `--model`, `-m` | Override the default model (e.g., `grok-4`) |

### How it Works

1. **Language Detection**: Grokkit detects the language using its internal linter.
2. **Context Analysis**: It reads the source file and any existing test file.
3. **AI Generation**: It sends the source code to Grok with a language-specific system prompt.
4. **Style Matching**: Grok is instructed to use modern idioms and match the project's testing style.
5. **Interactive Diff**: If a test file already exists, it shows a diff of the proposed changes.

### Best Practices

- **Start with unit tests**: Test individual functions and methods.
- **Run tests immediately**: After `testgen` completes, run `make test` or your language-specific test runner to verify the generated tests.
- **Review for accuracy**: AI-generated tests are a great starting point, but always review them to ensure the logic and assertions are correct.
- **Coverage**: Use `make test-cover` (for Go) to see how much your new tests have improved your coverage.