fileAssertion.js

/*
  Author: Ryan Paul
  Date: 12/03/18
  Description: Extracted code showing iterations over basic file existence functionality
  Environment: Node.js
*/

// Iteation 1: Initial attempt:
function isInstalled(installPath) {
  const fileNames = ['Game.exe', 'Diablo II.exe', 'd2data.mpq']
  const files = fileNames.map(file => path.join(installPath, file))
  const promises = files.map(file => accessAsync(file))

  return Promise.all(promises).then(assertAllTrue)

  function assertAllTrue(results) {
    return results.every(result => result === true)
  }
}


// Iteation 2: Async syntax version:
async function isInstalled(installPath) {
  const fileNames = ['Game.exe', 'Diablo II.exe', 'd2data.mpq']
  const files = fileNames.map(file => path.join(installPath, file))
  const promises = files.map(file => accessAsync(file))

  const results = await Promise.all(promises)
  return results.every(result => result === true)  
}


// Iteation 3: Fully inlined:
function isInstalled(installPath) {
  return Promise.all(
    ['Game.exe', 'Diablo II.exe', 'd2data.mpq']
      .map(file => accessAsync(path.join(installPath, file)))
  ).then(results => results.every(result => result === true))
}


// Iteration 4: Extract promise.all behavior into accessAsyncAll():
// (Not much gained from this, meh)
function isInstalled(installPath) {
  const files = ['Game.exe', 'Diablo II.exe', 'd2data.mpq']
    .map(file => path.join(installPath, file))
  
  return accessAllAsync(files).then(assertAllTrue)

  function assertAllTrue(array) {
    return array.every(value => value === true)
  }
}

// Conclusion: Combine iterations into most readable version:
async function isInstalled(installPath) {
  const promises = ['Game.exe', 'Diablo II.exe', 'd2data.mpq']
    .map(file => accessAsync(path.join(installPath, file)))
  
  const results = await Promise.all(promises)
  return results.every(value => value === true)
}