Testing · Code with Hugo

JavaScript Object.defineProperty for a function: create mock object instances in Jest or AVA

This post goes through how to use Object.defineProperty to mock how constructors create methods, ie. non-enumerable properties that are functions. The gist of Object.defineProperty use with a function value boils down to: const obj = {} Object.defineProperty(obj, 'yes', { ...

#Node #Testing #JavaScript

A testing guide for Express with request and response mocking/stubbing using Jest or sinon

To test an Express handler, it’s useful to know how to successfully mock/stub the request and response objects. The following examples will be written both using Jest and sinon (running in AVA). The rationale for this is the following. Jest is a very popular “all-in-one” testing ...

#Node #testing #JavaScript #Sequelize

Mocking/stubbing ES6 classes in tests with examples of Sequelize model unit tests

This post goes through some patterns that can be used to unit test ES6 classes. The examples will use Jest module auto-mocking but should be portable to other module mocking libraries (eg. Proxyquire) with some modifications. In “Using ES6 classes for Sequelize 4 models&rdq ...

#Testing #JavaScript #ES6

When to use Jest snapshot tests: comprehensive use-cases and examples 📸

There’s some nice use-cases for snapshot tests outside of the well-travelled React/Vue UI component ones. In other words, although React and Vue testing with snapshots is pretty well documented, that’s not the only place they’re useful. As a rule of thumb, you c ...

#JavaScript #Testing #Node

Mocking/stubbing the current Date in Jest tests

There are situations where Date.now is used in application code. That code needs to be tested, and it’s always a struggle to remember how to mock/stub Date.now. Here is the magic snippet: ...

#JavaScript #Node #Testing

Testing an Express app with SuperTest, moxios and Jest

Testing is a crucial part of the software development process. It helps to catch bugs, avoid regressions and to document the behaviour of a piece of software. Express is one of the most widespread libraries for building backend applications in JavaScript. What follows is a summar ...

#VueJS #testing #JavaScript

From AngularJS to Vue.js, CommonJS and Jest

The trials and tribulations of kicking off an AngularJS -> Vue.js migration AngularJS was pretty groundbreaking. It’s still impressive to this day, packed with a router, an HTTP client, a dependency injection system and a bunch of other things I haven’t necessarily had the p ...

#Testing #JavaScript #Productivity

AVA, low-config testing for JavaScript

A JavaScript testing library for 2017 AVA is a Futuristic JavaScript test runner. Some of its best features are: it works out of the box, no need to specify a blob for test files or add Babel hooks it’s runs tests in parallel, this stops you from using global state and runs fas ...