TypeScript Testing Skill

Overview

Master TypeScript testing including type-safe test setup, mocking with types, and testing type definitions.

Topics Covered

Test Setup

• Jest with ts-jest
• Vitest configuration
• ts-node for tests
• Path alias resolution
• Test coverage with types

Type-Safe Mocking

• Typed mock functions
• jest.Mocked utility
• vi.fn() typing
• Mock implementations
• Partial mocking

Type Testing

• tsd for type tests
• expect-type library
• Type assertion tests
• Compile-time testing
• Edge case type testing

Testing Patterns

• Generic test utilities
• Type-safe fixtures
• Builder patterns for tests
• Custom matchers with types
• Assertion type narrowing

Integration Testing

• API testing with types
• Database testing
• E2E type safety
• Request/response typing
• Test data factories

Prerequisites

• TypeScript fundamentals
• JavaScript testing basics

Learning Outcomes

• Write type-safe tests
• Test type definitions
• Create typed mocks
• Build test utilities