Example for interactive command testing with v4?

[Makeshift]

Is your feature request related to a problem? Please describe.
I'm developing a highly-interactive CLI application with oclif that utilises inquirer to perform setup with interaction from the user.

I'd like to test my CLI from the perspective of a potential user, exploring the results from answering these questions.

Without direct support for .stdin() in v4, it isn't clear to me how to achieve this with mock-stdin as suggested in the v4 migration docs.

Describe the solution you'd like
An example of how to use v4 to run tests against interactive CLIs.

Describe alternatives you've considered

• Revert to v3
• Test oclif and inquirer separately, implementing stubs to skip questions when testing oclif and using @inquirer/testing to render and test the outputs when testing interaction. I suspect this will be the suggested alternative, but I feel that it would result in not-particularly-representative tests for my application.

Additional context
Here's some code examples of what I'm working with currently:

test/commands/login.test.ts

import { runCommand } from '@oclif/test'
import { expect } from 'chai'
import { dirname, join } from 'node:path'
import { describe } from 'node:test'
import { fileURLToPath } from 'node:url'
// import { render } from '@inquirer/testing'
import { stdin as fstdin } from 'mock-stdin'

const _dirname = dirname(fileURLToPath(import.meta.url))
const root = join(_dirname, '..', '..')
const stdin = fstdin()

describe('command:init', () => {
  it('runs login', async () => {
    const { error, result, stderr, stdout } = await runCommand('login', { root })
    // of course, this won't work because the test fails before this due to it hanging waiting for user input
    stdin.send('\n')
    expect(result).to.equal(true)
  })
})

commands/login.ts

import { Command } from '@oclif/core'
import { confirm } from '@inquirer/prompts'

export class Login extends Command {
  static description = 'Placeholder'

  async run (): Promise<boolean> {
    const result = await confirm({
      message: 'Does this work?'
    })
    return result
  }
}

[mdonnalley]

@Makeshift Sorry I missed this!

To make your test work you should use captureOutput instead of runCommand. This will allow you to send the stdin using mock-stdin before running the command:

import {captureOutput} from '@oclif/test'
import {expect} from 'chai'
import {stdin as fstdin} from 'mock-stdin'
import {describe} from 'node:test'

import {Login} from '../../src/commands/login.js'

const stdin = fstdin()

describe('command:init', () => {
  it('runs login', async () => {
    const {result} = await captureOutput(async () => {
      setTimeout(() => stdin.send('y\n'), 10)
      return Login.run()
    })
    expect(result).to.equal(true)
  })
})

Test oclif and inquirer separately, implementing stubs to skip questions when testing oclif and using @inquirer/testing to render and test the outputs when testing interaction. I suspect this will be the suggested alternative, but I feel that it would result in not-particularly-representative tests for my application.

I think this is the best approach to be honest (and is really the only approach if you have more elaborate prompts that a single confirmation). But for single prompts, I think the example above would suffice for most people