@types/jest-when

What is @types/jest-when?

@types/jest-when is a TypeScript type definition package for the jest-when library, which provides a way to mock functions in Jest based on specific argument conditions. It enhances Jest's mocking capabilities by allowing more granular control over mock behavior.

What are @types/jest-when's main functionalities?

Mocking based on specific arguments

This feature allows you to mock a function to return different values based on the arguments it is called with. The code sample demonstrates how to set up a mock function that returns 'one' when called with 1, 'two' when called with 2, and undefined for any other arguments.

const when = require('jest-when');
const mockFn = jest.fn();
when(mockFn).calledWith(1).mockReturnValue('one');
when(mockFn).calledWith(2).mockReturnValue('two');

console.log(mockFn(1)); // 'one'
console.log(mockFn(2)); // 'two'
console.log(mockFn(3)); // undefined

Mocking based on multiple arguments

This feature allows you to mock a function based on multiple arguments. The code sample shows how to set up a mock function that returns 'one-a' when called with (1, 'a') and 'two-b' when called with (2, 'b').

const when = require('jest-when');
const mockFn = jest.fn();
when(mockFn).calledWith(1, 'a').mockReturnValue('one-a');
when(mockFn).calledWith(2, 'b').mockReturnValue('two-b');

console.log(mockFn(1, 'a')); // 'one-a'
console.log(mockFn(2, 'b')); // 'two-b'
console.log(mockFn(1, 'b')); // undefined

Mocking with default behavior

This feature allows you to set a default return value for a mock function, which will be used if none of the specific argument conditions are met. The code sample demonstrates a mock function that returns 'one' when called with 1 and 'default' for any other arguments.

const when = require('jest-when');
const mockFn = jest.fn().mockReturnValue('default');
when(mockFn).calledWith(1).mockReturnValue('one');

console.log(mockFn(1)); // 'one'
console.log(mockFn(2)); // 'default'

Other packages similar to @types/jest-when

jest-mock-extended

jest-mock-extended is a package that provides extended mocking capabilities for Jest, including type-safe mocks and deep mocks. It is similar to jest-when in that it enhances Jest's mocking capabilities, but it focuses more on type safety and deep mocking.

ts-mockito

ts-mockito is a mocking library for TypeScript inspired by the Java Mockito library. It provides a fluent API for creating mocks, stubs, and spies. Compared to jest-when, ts-mockito offers a more comprehensive and type-safe approach to mocking in TypeScript.

sinon

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README

Installation

npm install --save @types/jest-when

Summary

This package contains type definitions for jest-when (https://github.com/timkindberg/jest-when#readme).

Details

Files were exported from https://github.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/jest-when.

Additional Details

• Last updated: Tue, 07 Nov 2023 03:09:37 GMT
• Dependencies: @types/jest

Credits

These definitions were written by Alden Taylor, Trung Dang, Gregor Stamać, Nicholas Hehr, and Bogi Napoleon Wennerström.