@hexancore/mocker

Mocker

Two words can describe it: simple and magical :) Helper stuff to create mocks in TypeScript in Jest or Vitest

You just need it!

Usage:

In Jest

import { M, mock } from '@hexancore/mocker';

In Vitest

import { M, mock } from '@hexancore/mocker/vitest';

Example

import { M, mock } from '@hexancore/mocker';

interface TestMock {
  a(param1: string, param2: boolean): boolean;
  b(param1: string, param2: boolean): boolean;
}

describe('Example test suite', () => {
  let m: M<TestMock>; // Define mock variable with your class or interface wrapped with `M` type

  beforeEach(() => {
    // in beforeEach create `Mocker` with mock() factory method
    // you can simply mock interface or class and give it descriptive name(used in errors)
    m = mock('my_mock');
  });

  afterEach(() => {
    // after execute your code, you can check sets expectations results with it(for many tests call it in jest "afterEach")
    mock.checkExpections();
  });

  test('Example test', () => {
    // define method call expectation(available methods list will be shows in VS + it will hint all parameters and return type )
    m.expects('a', 'test', true).andReturn(true);

    // mock "i" property is object of mocked class, pass it where you need
    m.i.a('test', true);
  });

Defining expectation

Mocker::expects(method, ...args) returns MethodMock object with you can define return value by:

• andReturnWith((implementation: (...args: any) => any) - you can define your own method implementation
• andReturn(value: any) - define returns passed value once
• andReturnResolved - simple sugar function for andReturnWith((() => Promise.resolve(value))

Using Jest.expect matchers in Mocker.expects

let userRepository = mock<UserRepository>();
userRepository
      .expects('save', expect.objectContaining({ email, username, password: hashedPassword }))
      .andReturn(OKA(true));

Mockers

Manages a group of defined mocks in a more efficient way of writing test code and simplifing injecting many mocks to class object.

For use add to your tsconfig.json

 "compilerOptions": {
    "useDefineForClassFields": true,
 }

Example

import { mocks } from '@hexancore/mocker';

class TestMock {
  public method(a: number): number {
    return a * 2;
  }
}

class TestClassConstructor {
  public constructor(public mock1: TestMock, public readonly b: number, public mock2: TestMock) {}

  public method(): number {
    return mock1.method(this.b)+mock2.method(this.b);
  }
}

describe('Mockers', () => {
  // define variable using `mocks` and anonymous class with mocks you want create
  let m = mocks(
    new (class {
      mock1: TestMock;
      mock2: TestMock;
    })(),
  );

  // variable to create instance with injected mocks
  let testClass: TestClassConstructor;


  beforeEach(() => {
    // use xFresh() to get new Mockers instance
    // methods of Mockers using `x` prefix for be after your mocks names on VS list
    m = m.xFresh();

    // you can create new instance of your class with injected mocks and other parameters
    testClass = m.xNewInject(TestClassConstructor, { b: 10 });

    // other non mock parameters can be given as object or array
    // testClass = m.xNewInject(TestClassConstructor, [10]);
  });

  afterEach(() => {
    m.xCheckExpections(); // checks all mocks expections
  });

  test('test()', () => {
    m.mock1.expects('method', 10).andReturn(5);
    m.mock2.expects('method', 10).andReturn(6);

    const current = testClass.method();
  });