Validates that the versions of tools specified in `engines` in the package.json are installed on the machine.

package.json

{
  "name": "workshop-computer-validator",
  "version": "1.0.0",
  "description": "I use this to validate people's computers have the proper versions of node and npm installed for a workshop",
  "bin": "./validate-system.js",
  "dependencies": {
    "semver": "7.1.3"
  }
}

validate-system.js

#!/usr/bin/env node

var path = require('path')
var execSync = require('child_process').execSync
var semver = require('semver')

var specified = process.argv[2]
var cwd = specified
  ? path.isAbsolute(specified)
    ? specified
    : path.join(process.cwd(), specified)
  : process.cwd()
var pkg = require(path.join(cwd, 'package.json'))

function validateVersion(desired, command, message) {
  var actual = '0.0.0'
  try {
    actual = execSync(command)
      .toString()
      .trim()
  } catch (error) {
    return (
      'There was an error running the command `' +
      command +
      '`:\n' +
      error.message
    )
  }
  return semver.satisfies(actual, desired) ? null : message(actual, desired)
}

var messages = {
  node: function(actual, desired) {
    return (
      'This computer has node@' +
      actual +
      ' installed, but node@' +
      desired +
      ' is required. Please update node: https://nodejs.org'
    )
  },
  npm: function(actual, desired) {
    return (
      'This computer has npm@' +
      actual +
      ' installed, but npm@' +
      desired +
      ' is required. Please update npm by running `npm install --global npm@' +
      desired +
      '`.'
    )
  },
  git: function(actual, desired) {
    return (
      'This computer has git@' +
      actual +
      ' installed, but git@' +
      desired +
      ' is required. Please install the proper version of git https://git-scm.com/book/en/v2/Getting-Started-Installing-Git'
    )
  }
}

var validators = {
  node: function(desired) {
    return validateVersion(desired, 'node --version', messages.node)
  },
  npm: function(desired) {
    return validateVersion(desired, 'npm --version', messages.npm)
  },
  git: function(desired) {
    var actual = '0.0.0'
    try {
      const versionOutput = execSync('git --version')
        .toString()
        .trim()
      try {
        actual = versionOutput
          .match(/git version (?<version>\d+\.\d+\.\d+)/)
          .groups
          .version
      } catch (error) {
        return (
          'There was an error extracting the git version ' +
          'from the git --version output:\n' +
          versionOutput +
          '\n\nIt should say "git version NUMBER.NUMBER.NUMBER" but' +
          'did not. Please report this error output!'
        )
      }
    } catch (error) {
      return (
        'There was an error running the command `' +
        command +
        '`:\n' +
        error.message
      )
    }
    return semver.satisfies(actual, desired) ? null : messages.git(actual, desired)
  },
}

var errors = Object.keys(pkg.engines)
  .map(function(engine) {
    if (!validators[engine]) {
      throw new Error('Engine "' + engine + '" is unsupported.')
    }
    return validators[engine](pkg.engines[engine])
  })
  .filter(Boolean)

if (errors.length) {
  console.error(
    'There were errors validating the compatibility of this computer:',
  )
  console.error('\n    ' + errors.join('\n    ') + '\n\n')
  console.error(
    'If you would like to just ignore this error, then feel free to do so and install dependencies as you normally would in "' +
      cwd +
      '". Just know that things may not work properly if you do...',
  )

  process.exit(1)
}

This doesn't seem to work for node version 15

Whats the error?

This doesn't seem to work for node version 15

Whats the error?

This doesn't seem to work for node version 15

It says to only use between node versions 10 and 14

The latest version of all the workshops allow for Node 15 now.

@kentcdodds would you add support to Node 19 too?

That is configured in the package.json of the workshops. Feel free to open a pull request if you'd like.