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TypeScript Academy · Lesson

Mocking Modules and Functions in TypeScript

Use jest.mock with correct type casting strategies.

Welcome

Jest module mocking with TypeScript requires correct type casting strategies to avoid any-typed mocks.

jest.fn() with Types

Type a jest mock function with its signature.
const mockFn = jest.fn<number, [string]>();
mockFn('hello'); // typed call

All lessons in this course

  1. Jest Setup for TypeScript with ts-jest
  2. Writing Type-Safe Unit Tests
  3. Mocking Modules and Functions in TypeScript
  4. Type Testing with expectTypeOf and tsd
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