generate-unit-tests

Description

This skill analyzes the currently selected code and generates a comprehensive unit test suite using the project's testing framework (Jest or Vitest).

When to use

• •You have an existing function, class, or module without tests.
• •You are refactoring code and want to lock in behavior before changes.
• •You want to improve coverage for critical business logic.

Instructions

1. •Read the selected code and infer its behavior and edge cases.
2. •Identify:
   • •Happy Path scenarios (valid inputs and expected outputs).
   • •Edge Cases (empty inputs, null/undefined, boundary values).
   • •Error Cases (exceptions, rejected promises, invalid inputs).
3. •Choose the correct test framework:
   • •Use Jest or Vitest depending on what the project already uses.
4. •Generate a test file that:
   • •Follows the Arrange–Act–Assert pattern.
   • •Groups related tests with clear describe blocks.
   • •Uses mocks or test doubles for external dependencies.
5. •Ensure tests are:
   • •Deterministic and fast.
   • •Easy to read and maintain.
6. •At the end, briefly summarize what behavior is covered and what is intentionally not covered.

Examples

Example input (user intent)

Generate unit tests for this calculateTotal function.

Example output (high level)

• •A calculateTotal.test.ts file using Vitest.
• •Tests for positive numbers, zero, negative numbers, and invalid input.
• •Mocking of any external dependencies (e.g. discount service).