console.Console global reference is undefined in the node environment

[twawszczak]

🐛 Bug Report

Regarding official documentation, in the nodeJS environment it is possible to create Console object with global console reference:

const { Console } = console;
const instance = new Console(..);

With jest, configured as a node instance, it doesn't work:

jest.config.js:

module.exports = {
  testEnvironment: 'node'
};

console.test.js:

test('console.Console should not be undefined in the node environment', () => {
    expect(console.Console).not.toBeUndefined();
});

output:

    expect(received).not.toBeUndefined()

    Received: undefined

      1 | test('console.Console should not be undefined in the node environment', () => {
    > 2 |     expect(console.Console).not.toBeUndefined();
        |                                 ^
      3 | });
      4 | 

      at Object.<anonymous> (console.test.js:2:33)

To Reproduce

Steps to reproduce the behavior: just check the simple demo repo linked below

Expected behavior

Global console.Console reference should be defined in the nodeJS environment.

Link to repl or repo (highly encouraged)

https://github.com/twawszczak/jest-console-issue

envinfo

  System:
    OS: macOS 10.15.4
    CPU: (8) x64 Intel(R) Core(TM) i5-8279U CPU @ 2.40GHz
  Binaries:
    Node: 12.16.3 - ~/.nvm/versions/node/v12.16.3/bin/node
    Yarn: 1.22.4 - ~/.nvm/versions/node/v12.16.3/bin/yarn
    npm: 6.14.4 - ~/.nvm/versions/node/v12.16.3/bin/npm
  npmPackages:
    jest: ^26.1.0 => 26.1.0 

[jeysal]

Thanks for the issue, accepting PRs to add Console to our custom console object! One discussion point is probably whether we want to expose the actual Node.JS console class or the custom console class.

[Mark1626]

@jeysal I'll pick it up

BufferedConsole:

Pretty straightforward, the following is valid

export default class BufferedConsole extends Console {

  constructor() { }

  static Console: NodeJS.ConsoleConstructor = BufferedConsole;

CustomConsole:

Not straight forward because of the base class. I thought of the following two ways

export default class CustomConsole extends Console {

  constructor(
    stdout: NodeJS.WriteStream,
    stderr: NodeJS.WriteStream,
    formatBuffer: Formatter) {
  }

  CustomConsole: CustomConsoleContructor = CustomConsole;
  // ...
}

export default class CustomConsole extends Console {

  constructor(
    stdout: NodeJS.WriteStream,
    stderr: NodeJS.WriteStream,
    formatBuffer: Formatter) {
  }

  Console: NodeJS.ConsoleContructor = Console;
  //...
}

Maybe this may be an approach, if the class does not extend Console.
I created an instance of console to use in _log and _warn.
Not sure how viable this is, exploring it as a possibility

export default class CustomConsole {
  private _console: Console;

  constructor(
    stdout: NodeJS.WriteStream,
    stderr: NodeJS.WriteStream,
    formatBuffer: Formatter = (_type: LogType, message: string): string =>
      message,
  ) {
    this._console = new Console(stdout, stderr);
  }

  Console: CustomConsoleContructor = CustomConsole;

private _log(type: LogType, message: string) {
    clearLine(this._stdout);
    this._console.log(
      this._formatBuffer(type, '  '.repeat(this._groupDepth) + message),
    );
  }

  private _logError(type: LogType, message: string) {
    clearLine(this._stderr);
    this._console.error(
      this._formatBuffer(type, '  '.repeat(this._groupDepth) + message),
    );
  }

Any thoughts? I'll get started on a PR when we finished discussion

[jeysal]

Not sure I understand how it's more difficult for CustomConsole than BufferedConsole 'because of the base class', they both have Console as their base class right?
Either way, in case we decide to expose the 'standard' console, static Console = OriginalConsole; would suffice and not cause any further complications, right?
I think this decision would be a valid choice, since afaik creating Console instances is mostly done if you want to direct to a stream other than stdout/stderr, and in that case people might expect it to print 'normal' console messages rather than Jest-formatted ones. wdyt @SimenB?

[github-actions]

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