https://github.com/hustcc/jest-random-mock

🎲 Mock Math.random in jest, with deterministic random number.
https://github.com/hustcc/jest-random-mock

Last synced: 3 months ago
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🎲 Mock Math.random in jest, with deterministic random number.

• Host: GitHub
• URL: https://github.com/hustcc/jest-random-mock
• Owner: hustcc
• License: mit
• Created: 2024-02-23T09:07:51.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2024-02-24T06:53:50.000Z (over 1 year ago)
• Last Synced: 2025-01-12T09:19:07.727Z (5 months ago)
• Language: JavaScript
• Size: 4.88 KB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# jest-random-mock

> Mock `Math.random` when run unit test cases with jest, output deterministic random number.

[![Build Status](https://github.com/hustcc/jest-random-mock/workflows/build/badge.svg)](https://github.com/hustcc/jest-random-mock/actions)

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## Install

This should only be installed as a development dependency (`devDependencies`) as it is only designed for testing.

```bash

$ npm i --save-dev jest-random-mock

```

## Usage

> Use the only `3 api` for test cases.

 - `mock()`: Mocks the Math.random, with deterministic random function.

 - `clear()`: Shut down the mock system, use original Math.random.

 - `createDeterministicRandom()`: Return a deterministic random number generator.

Use it in jest env.

```js

import { mock, clear } from "jest-random-mock";

beforeEach(() => {

  mock();

});

test("your test cases", () => {

  mock();

  const r1 = Math.random();

  clear();

  mock();

  const r2 = Math.random();

  clear();

  // expect r1 should be same with r2.

});

afterEach(() => {

  clear();

});

```

Use it as a library.

```ts

import { createDeterministicRandom } from "jest-random-mock";

const random = createDeterministicRandom();

const v1 = random();

const v2 = random();

```

## Random distribution

![image](https://github.com/hustcc/jest-random-mock/assets/7856674/a2601adf-984c-4ecc-aa8f-d247a2ab6141)

```ts

import { Chart } from "@antv/g2";

import { createDeterministicRandom } from "jest-random-mock";

const random = createDeterministicRandom();

const chart = new Chart({

  container: "container",

  autoFit: true,

  theme: "academy",

});

const flex = chart

  .spaceFlex()

  .attr("direction", "row")

  .attr("ratio", [1, 1, 1]);

const TIMES = [100, 1000, 10000];

TIMES.forEach((time) => {

  const data = new Array(time).fill(0).map(() => ({ v: random() }));

  flex

    .rect()

    .data(data)

    .encode("x", "v")

    .encode("color", "steelblue")

    .transform({ type: "binX", y: "count", thresholds: 10 })

    .style("inset", 0.5)

    .axis("x", { title: false })

    .axis("y", { title: `${time} times Radnom` });

});

chart.render();

```

## License

MIT@[hustcc](https://github.com/hustcc).