Testing

With Jest it’s possible to assert of single or specific arguments/parameters of a mock function call with .toHaveBeenCalled/.toBeCalled and expect.anything(). The full example repository is at github.com/HugoDF/jest-specific-argument-assert, more specifically lines 17-66 i ...

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', { ...

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 ...

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 ...

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 ...

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 pl ...

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 runs tests in parallel, this stops you from using global state and runs faster ...