https://github.com/EpicEric/jest-mock-process

Easily mock NodeJS process properties in Jest.
https://github.com/EpicEric/jest-mock-process

console-log exitcode jest nodejs stderr stdout

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Easily mock NodeJS process properties in Jest.

• Host: GitHub
• URL: https://github.com/EpicEric/jest-mock-process
• Owner: EpicEric
• License: mit
• Created: 2018-07-30T21:03:47.000Z (over 6 years ago)
• Default Branch: main
• Last Pushed: 2022-06-30T17:45:04.000Z (over 2 years ago)
• Last Synced: 2024-04-26T05:23:43.586Z (8 months ago)
• Topics: console-log, exitcode, jest, nodejs, stderr, stdout
• Language: TypeScript
• Homepage:
• Size: 322 KB
• Stars: 27
• Watchers: 2
• Forks: 7
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# jest-mock-process [![npm version](https://badge.fury.io/js/jest-mock-process.svg)](https://www.npmjs.com/package/jest-mock-process) [![CircleCI](https://circleci.com/gh/EpicEric/jest-mock-process/tree/main.svg?style=svg)](https://circleci.com/gh/EpicEric/jest-mock-process/tree/main) [![Coverage Status](https://coveralls.io/repos/github/EpicEric/jest-mock-process/badge.svg?branch=main)](https://coveralls.io/github/EpicEric/jest-mock-process?branch=master)

Easily mock NodeJS process properties in Jest.

## Installation

```sh

npm install --save-dev jest-mock-process

```

## Usage

TypeScript example.

```typescript

import {

  mockProcessExit,

  mockProcessStdout,

  mockProcessStderr,

  mockProcessUptime,

  mockConsoleLog,

} from "jest-mock-process";

let mockExit = mockProcessExit();

process.exit(1);

expect(mockExit).toHaveBeenCalledWith(1);

mockExit = mockProcessExit(new Error("Mock"));

expect(() => process.exit(0)).toThrowError("Mock");

const mockStdout = mockProcessStdout();

process.stdout.write("Hello, world!");

expect(mockStdout).toHaveBeenCalledWith("Hello, world!");

const mockStderr = mockProcessStderr();

process.stderr.write("Error");

expect(mockStderr).toHaveBeenCalledWith("Error");

const mockUptime = mockProcessUptime(3.14159);

const uptimeValue = process.uptime();

expect(uptimeValue).toEqual(3.14159);

const mockLog = mockConsoleLog();

console.log("Browser log");

expect(mockLog).toHaveBeenCalledWith("Browser log");

mockExit.mockRestore();

mockStdout.mockRestore();

mockStderr.mockRestore();

mockUptime.mockRestore();

mockLog.mockRestore();

```

### Advanced usage

- You can use `mockedRun` (or `asyncMockedRun`) to set-up a virtual environment that will automatically create and restore provided mocks:

```typescript

import { mockedRun, MockedRunResult } from "jest-mock-process";

const mockRun = mockedRun({

  stdout: mockProcessStdout,

  stderr: mockProcessStderr,

  exit: mockProcessExit,

  log: mockConsoleLog,

});

const mockEnvironment = mockRun(() => {

  process.stdout.write("stdout payload");

  process.stderr.write("stderr payload");

  process.exit(-1);

  console.log("log payload");

  return 10;

});

expect(mockEnvironment.result).toEqual(10);

expect(mockEnvironment.error).toBeUndefined();

expect(mockEnvironment.mocks.stdout).toHaveBeenCalledTimes(1);

expect(mockEnvironment.mocks.log).toHaveBeenCalledWith("log payload");

```

**NOTE: The above is a breaking change in version 2.0.0, as the provided mocks are now limited to the `mocks` object.**

- You can mock generic methods not supported by default in `jest-mock-process` with the `spyOnImplementing` function:

```typescript

import { spyOnImplementing } from "jest-mock-process";

const mockStdin = spyOnImplementing(process.stdin, "read", () => "");

process.stdin.read(1024);

expect(mockStdin).toHaveBeenCalledWith(1024);

```