@chubbyts/chubbyts-function-mock/README.md

A function mock helper.

# chubbyts-function-mock

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## Description

A function mock helper.

**IMPORTANT**: `deepStrictEqual` is used for parameter comparsion, `===` if you pass `strict: true`

## Requirements

 * node: 18

## Installation

Through [NPM](https://www.npmjs.com) as [@chubbyts/chubbyts-function-mock][1].

```sh
npm i @chubbyts/chubbyts-function-mock@2.0.2
```

## Usage

### createFunctionMock

```ts
import { expect, test } from '@jest/globals'; // or 'vitest'
import { useFunctionMock } from '@chubbyts/chubbyts-function-mock/dist/function-mock';

type MyFunction = (string: string, start: number, stop: number) => string;

test('my random test', () => {
  const [myFunction, myFunctionMocks] = useFunctionMock<MyFunction>([
    { parameters: ['test', 0, 2], return: 'te' },
    {
      callback: (string: string, start: number, stop: number): string => {
        expect(string).toBe('test');
        expect(start).toBe(1);
        expect(stop).toBe(2);

        return 'es';
      }
    },
    { parameters: ['test', 0, 2], error: new Error('test') },
  ]);

  expect(myFunction('test', 0, 2)).toBe('te');
  expect(myFunction('test', 1, 2)).toBe('es');

  try {
    expect(myFunction('test', 2, 2)).toBe('st');
    throw new Error('Expect fail');
  } catch (e) {
    expect(e).toMatchInlineSnapshot('[Error: test]');
  }

  // if you want to be sure, that all mocks are called
  expect(myFunctionMocks.length).toBe(0);
});
```

### createObjectMock

**IMPORTANT**: Do not use with spread operator `...myObject`!.

```ts
import { expect, test } from '@jest/globals'; // or 'vitest'
import { useObjectMock } from '@chubbyts/chubbyts-function-mock/dist/object-mock';

type MyType = {
  substring: (string: string, start: number, stop: number) => string;
  uppercase: (string: string) => string;
};

test('my random test', () => {
  const [myObject, myObjectMocks] = useObjectMock<MyType>([
    { name: 'substring', parameters: ['test', 0, 2], return: 'te' },
    {
      name: 'substring',
      callback: (string: string, start: number, stop: number): string => {
        expect(string).toBe('test');
        expect(start).toBe(1);
        expect(stop).toBe(2);

        return 'es';
      }
    },
    { name: 'uppercase', parameters: ['test'], error: new Error('test') },
  ]);

  expect(myObject.substring('test', 0, 2)).toBe('te');
  expect(myObject.substring('test', 1, 2)).toBe('es');

  try {
    expect(myObject.uppercase('test')).toBe('st');
    throw new Error('Expect fail');
  } catch (e) {
    expect(e).toMatchInlineSnapshot('[Error: test]');
  }

  // if you want to be sure, that all mocks are called
  expect(myObjectMocks.length).toBe(0);
});
```

## Copyright

2025 Dominik Zogg

[1]: https://www.npmjs.com/package/@chubbyts/chubbyts-function-mock