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Test-Driven Development With The oclif Testing Library: Part Two

In Part One of this series on the oclif testing library, we used a test-driven development approach to building our time-tracker CLI. We talked about the oclif framework, which helps developers dispense with the setup and boilerplate so that they can get to writing the meat of their CLI applications. We also talked about @oclif/test and @oclif/fancy-test, which take care of the repetitive setup and teardown so that developers can focus on writing their Mocha tests.

Our time-tracker application is a multi-command CLI. We’ve already written tests and implemented our first command for adding a new project to our tracker. Next, we’re going to write tests and implement our “start timer” command.

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Running Concurrent Requests With Async/Await and Promise.all

Introduction

In this article, I'd like to touch on async, await, and Promise.all in JavaScript. First, I'll talk about concurrency vs. parallelism and why we will be targeting parallelism in this article. Then, I'll talk about how to use async and await to implement a parallel algorithm in serial and how to make it work in parallel by using Promise.all. Finally, I'll create an example project using Salesforce's Lightning Web Components where I will build an art gallery using Harvard's Art Gallery API.

Concurrency vs. Parallelism

I want to quickly touch on the difference between concurrency and parallelism. You can relate concurrency to how a single-threaded CPU processes multiple tasks. Single-threaded CPUs emulate parallelism by switching between processes quickly enough that it seems like multiple things are happening at the same time. Parallelism is when a CPU has multiple cores and can actually run two tasks at the exact same time. Another great example is this: