Test for missing translations in i18n

testMissingTranslations.js

import I18n from 'i18n'
const deepKeys = require('deep-keys');

const NO_DIFF = null

Object.defineProperty(Object.prototype, 'translations', {
  get: function() {
    let locale = Object.keys(this)[0]
    return [ locale, this[locale] ]
  }
});

/**
 * Checks that both JSON objects have the same keys.
 * @param  {JSON} a Translations for a specific locale
 * @param  {JSON} b Translations for another locale
 * @return {JSON}   Differences between both objects
 */
function diff(a,b) {
  let [ aLocale, aTranslations ] = a.translations
  let [ bLocale, bTranslations ] = b.translations

  /**
   * Extract only keys from JSON
   * @return {Array}
   *
   * Example:
   * deepKeys({a: {b: {c: 1}}})
   * Result: [ 'a.b.c' ]
   */
  a = deepKeys(aTranslations)
  b = deepKeys(bTranslations)

  let missingInB = a.filter(x => b.indexOf(x) == -1)
  let missingInA = b.filter(x => a.indexOf(x) == -1)

  if (missingInA.length === 0 && missingInB.length === 0 ) {
    return NO_DIFF
  }

  return { [aLocale]: missingInB, [bLocale]: missingInA }
}

/**
 * Checks that all JSON objects have the same keys.
 * @param  {...Array} objects Array of translations
 * @return {JSON}            Differences between JSON objects.
 */
function diffs(...objects) {
  let results = {}

  objects.forEach(function(o1) {
    objects.forEach(function(o2) {

      // Pairwise comparison of objects
      let diffBetweenObjects = diff(o1,o2)
      if (diffBetweenObjects !== NO_DIFF) {
        // Store differences
        results = {...results, ...diffBetweenObjects}
      }

    })
  })

  return results
}

/**
 * Test for equality in translation keys.
 * @return {Bool}     True if all translations have the same keys.
 */
test('no missing translations', () => {
  let formattedTranslations = []
  for(let o in I18n.translations) {
    formattedTranslations.push({[o]: I18n.translations[o]})
  }
  let diff = diffs(...formattedTranslations)
  expect(diff).toEqual({});
});

Test missing translations in i18n

Check if there are missing keys in multiple JSON objects containing translations for different locales.

Requirements

• Jest

$ yarn add --dev jest

• deep-keys

$ yarn add deep-keys