outside-in-testing

# Outside-In Testing Skill

## Purpose [LEVEL 1]

This skill helps you create **agentic outside-in tests** that verify application behavior from an external user's perspective without any knowledge of internal implementation. Using the gadugi-agentic-test framework, you write declarative YAML scenarios that AI agents execute, observe, and validate.

**Key Principle**: Tests describe WHAT should happen, not HOW it's implemented. Agents figure out the execution details.

## When to Use This Skill [LEVEL 1]

### Perfect For

- **Smoke Tests**: Quick validation that critical user flows work
- **Behavior-Driven Testing**: Verify features from user perspective
- **Cross-Platform Testing**: Same test logic for CLI, TUI, Web, Electron
- **Refactoring Safety**: Tests remain valid when implementation changes
- **AI-Powered Testing**: Let agents handle complex interactions
- **Documentation as Tests**: YAML scenarios double as executable specs

### Use This Skill When

- Starting a new project and defining expected behaviors
- Refactoring code and need tests that won't break with internal changes
- Testing user-facing applications (CLI tools, TUIs, web apps, desktop apps)
- Writing acceptance criteria that can be automatically verified
- Need tests that non-developers can read and understand
- Want to catch regressions in critical user workflows
- Testing complex multi-step interactions

### Don't Use This Skill When

- Need unit tests for internal functions (use test-gap-analyzer instead)
- Testing performance or load characteristics
- Need precise timing or concurrency control
- Testing non-interactive batch processes
- Implementation details matter more than behavior

## Core Concepts [LEVEL 1]

### Outside-In Testing Philosophy

**Traditional Inside-Out Testing**:

```python
# Tightly coupled to implementation
def test_calculator_add():
    calc = Calculator()
    result = calc.add(2, 3)
    assert result == 5
    assert calc.history == [(2, 3, 5)]  # Knows internal state