How to use extraIfPackageJson method in Jest

Ok, I am now sitting in the corner with my dunce hat on.

Found this: https://github.com/istanbuljs/nyc/issues/35#issuecomment-121008298

Uncovered Lines = 17 isn't a count of the uncovered lines, it's a list with only one value, that is, line 17: total: total || 1,.

Fixed with...

test('passing zero forces the default total of 1', () => {
  const bar = progressBar(0)
  expect(bar.total).toBe(1)
})

A simple way around this is to use the standard .toContain() matcher (https://jestjs.io/docs/en/expect#tocontainitem) and reverse the expect statement:

expect([1, -2, 22]).toContain(someNumber);

More than likely, your UserService class has other dependencies and as such, Nest cannot instantiate the UserService class. When you are trying to do userService = module.get(UserService) you are retrieving an undefined hence the error about jest.spyOn(). In unit tests, you should be providing a mock provider to take the place of your actual provider, like so:

describe("User Controller", () => {
  let usercontroller: UserController;
  let userservice: UserService;
  // let fireBaseAuthService: FireBaseAuthService;
  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      controllers: [UserController],
      providers: [
        {
          provide: UserService,
          useValue: {
            updateUser: jest.fn(),
            // other UserService methods
          }
        }
      ],
    }).compile();

    usercontroller = module.get<UserController>(UserController);

    userservice = module.get<UserService>(UserService);
  });
  // rest of tests
});

Now when you retrieve the UserService you'll have an object with the proper functions back, which can then be jest.spyOned and mocked

Another possibility is that ts-jest is slow. There was an issue about that, and it was not completely resolved.

There are various workarounds discussed. They consist of setting isolatedModules=true and also --maxWorkers=1. That is, in jest.config.js

'use strict';

module.exports = {
    preset: 'ts-jest',
    testEnvironment: 'node',
    globals: {
        'ts-jest': {
            isolatedModules: true
        }
    },
}

and run

yarn test --maxWorkers=1

Could be worth trying. Alternatively, it is possible to forgo ts-jest and use babel transpilation.

I've had similar results when there was Proxy and/or certificate issues blocking things.

What I would do is first enable logging: firebase.database.enableLogging(true);

Then take a look at what it says. If you can't see what is blocking I'd then run Wireshark, we were able to see what was happening then.

OK, I've figured it out. The trick is, to split functions into separate files. So the code is (and works in https://repl.it/languages/jest ):

// add.js
child = require('./child').child;

function main(a) {
  if (a == 2) {
    child(a + 2);
  }

  return a + 1;
}

exports.main = main;

extracted child.js file:

// child.js

function child(ch) {
   const t = ch + 1;
   // no return value here. Function has some other "side effect"
}

exports.child = child;

main test file:

// add-spec.js
main = require('./add').main;
child = require('./child').child;

child = jest.fn();

describe('main', () => {

  it('should add one and not call child Fn', () => {
    expect(main(1)).toBe(2);

    expect(child).toHaveBeenCalledTimes(0);
  });

  it('should add one andcall child Fn', () => {
    expect(main(2)).toBe(3);

    expect(child).toHaveBeenCalledWith(4);
    expect(child).toHaveBeenCalledTimes(1);
  });

});

You have to use global to access objects in the global context

global.console = {warn: jest.fn()}
expect(console.warn).toBeCalled()

or use jest.spyOn added in 19.0.0

jest.spyOn(global.console, 'warn')

[Edit] I don't know if the question was edited after I added the answer or I just didn't understand the question correctly, but my answer describes how to resolve the error in testing environment.

If you have this issue out of testing environment - this answer will not help you, sorry.

Late for the party, but just had to resolve the same issue, so I'll leave it here just in case.

One way to resolve the problem as mentioned here is:

const wrapper = mount(MyComponent, {
  mocks: {
    // Always returns the input
    $t: i => i,
    localePath: i => i
  }
});

However, I've recently found a better way:

./tests/jest.setup.js:

// https://github.com/nuxt/nuxt.js/issues/4115
import Vue from 'vue'
import { config } from '@vue/test-utils'

Vue.config.silent = true

// Mock Nuxt components
config.stubs['nuxt-link'] = true; // string stabs like '<a><slot /></a>' are now depreciated
config.stubs['no-ssr'] = true;
config.mocks.$t = i => i;
config.mocks.localePath = i => i;

./jest.config.js:

module.exports = {
  setupFiles: [
    '<rootDir>/tests/jest.setup.js'
  ],
  moduleNameMapper: {
    '^@/(.*)$': '<rootDir>/$1',
    '^~/(.*)$': '<rootDir>/$1',
    '^vue$': 'vue/dist/vue.common.js'
  },
  moduleFileExtensions: ['js', 'vue', 'json'],
  transform: {
    '^.+\\.js$': 'babel-jest',
    '.*\\.(vue)$': 'vue-jest'
  },
  collectCoverage: true,
  collectCoverageFrom: [
    '<rootDir>/components/**/*.vue',
    '<rootDir>/pages/**/*.vue'
  ],
  testPathIgnorePatterns: [
    'node_modules',
    'cypress',
  ],
}

Surprisingly enough, I don't need to install ts-jest package at least now even though I use Nuxt Typescript.

Then in each test suite I need to use the mock I've already mentioned on top of this answer.

Use the following code to set up the crypto property globally. It will allow Jest to access

• window.crypto in the browser environment
• global.crypto in non-browsers environments. (Node/Typescript scripts).

It uses the globalThis which is now available on most of the latest browsers as well as Node.js 12+

const crypto = require('crypto');

Object.defineProperty(globalThis, 'crypto', {
  value: {
    getRandomValues: arr => crypto.randomBytes(arr.length)
  }
});