chai_jest_mocks.md

layout	permalink	pluginName
plugin	plugins/chai-jest-mocks/	chai-jest-mocks

chai-jest-mocks

Chai plugin that adds assertions for jest mock functions

NOTE this is still very much a work in progress, more matchers and better documentation (and tests) are coming!

Installation

On the command line:

$ npm install --save-dev chai-jest-mocks

Usage

First, tell chai that you want to use chai-jest-mocks

const chai = require('chai');
const chaiJestMock = require('chai-jest-mocks');

chai.use(chaiJestMock);

Then you will have access to the new assertions:

// Expect a mock to be called
expect(mockFn).to.have.beenCalled();

// Expect a mock to have been called a certain number of times
expect(mockFn).to.have.beenCalledTimes(4);

// Expect a mock to have been called with specific arguments
expect(mockFn).to.have.beenCalledWith('hello', 'world');

// Expect a mock to have been last called with specific arguments
expect(mockFn).to.have.beenLastCalledWith('hello', 'world');

// Expect a mock to have been nth (in this case, second) called with specific arguments
expect(mockFn).to.have.beenNthCalledWith(2, 'hello', 'world');

// Expect a mock to have returned succesfully (i.e, not throw)
expect(mockFn).to.have.returned();

// Expect a mock to have returned succesfully a certain number of times
expect(mockFn).to.have.returnedTimes(3);