Write unit tests for a chosen function with a Copilot prompt file

---
agent: 'agent'
description: 'Generate unit tests for selected functions or methods'
---

## Task

Analyze the selected function/method and generate focused unit tests that thoroughly validate its behavior.

## Test Generation Strategy

1. **Core Functionality Tests**
   - Test the main purpose/expected behavior
   - Verify return values with typical inputs
   - Test with realistic data scenarios

2. **Input Validation Tests**
   - Test with invalid input types
   - Test with null/undefined values
   - Test with empty strings/arrays/objects
   - Test boundary values (min/max, zero, negative numbers)

3. **Error Handling Tests**
   - Test expected exceptions are thrown
   - Verify error messages are meaningful
   - Test graceful handling of edge cases

4. **Side Effects Tests** (if applicable)
   - Verify external calls are made correctly
   - Test state changes
   - Validate interactions with dependencies

## Test Structure Requirements

- Use existing project testing framework and patterns
- Follow AAA pattern: Arrange, Act, Assert
- Write descriptive test names that explain the scenario
- Group related tests in describe/context blocks
- Mock external dependencies cleanly

Target function: ${input:function_name:Which function or method should be tested?}
Testing framework: ${input:framework:Which framework? (jest/vitest/mocha/pytest/rspec/etc)}

## Guidelines

- Generate 5-8 focused test cases covering the most important scenarios
- Include realistic test data, not just simple examples
- Add comments for complex test setup or assertions
- Ensure tests are independent and can run in any order
- Focus on testing behavior, not implementation details

Create tests that give confidence the function works correctly and help catch regressions.