Klingon Translation Service

Story

In this exercise you'll be providing a TranslationService where paid members have some quality assurance.

You have found a magical translation API that is able to fulfill any translation request in a reasonable amount of time, and you want to capitalize on this.

The magical API has a very minimal interface:

Fetching a translation

api.fetch(text) fetches the translation of text, returning two values:

  • translation: the actual translation
  • quality: the quality expressed as a number

If there is no translation available (because it has not been requested yet), the API throws an error. This also happens if a piece of text is untranslatable.

Requesting a translation

api.request(text, callback) requests the translation of text, calling the callback once it's ready, without a value.

The request API is unstable, which means that sometimes the API will call the callback with an error. If that happens, it is okay to re-request.

âš  Warning! âš 

Because of some previous users being lazy when programming, always requesting a translation, without even checking if the text was already translated, the API returns an error if the text has already been translated and blocks all access completely, forever.

Tasks

These These are examples of tasks that fit the story of the translation service:

  • Fetch a translation, ignoring the quality
  • Fetch a batch of translations, all-or-nothing
  • Request a translation, retrying at most 2 times
  • Fetch a translation, inspect the quality, or request it

Terminology

These are recommendations, not rules, for recurring terminology in the instructions (including stub commentary)

  • The injected dependency is called the TranslationService, or API
  • The service is async, but this is never mentioned
  • A failure on a Future is the API throws an error
  • A failure on a Callback is the API will call callback with an error

All the translation texts are Klingon to English.

Implementations

Reference

N.B.

The correct translation of 'arlogh Qoylu'pu'? is How many times has it been heard?.