How to Write File-Based Tests With Real Files

• mock-fs

  2 896 0.0 JavaScript

  Configurable mock for the fs module

A lot of my past projects in some way had to do with file access. I started to test with mocking libraries like mock-fs, but soon recognized that they do not work for all cases, and sometimes you are using third party libraries internally that you cannot mock easily. So I thought of a different solution and the one I'm using right now for most projects actually uses real files.

• with-local-tmp-dir

  1 4 4.9 JavaScript

  Creates a temporary folder inside cwd, cds inside the folder, runs a function, and removes the folder. Especially useful for testing.

Why not use real files for testing instead of mocking? I built an NPM package called with-local-tmp-dir that basically creates a temporary subfolder inside cwd, cds into it, runs a function, and cds back to the previous cwd afterwards. In this function you can create files and pretty much anything, run your unit under test. Afterwards the folder is removed and everything is cleaned up. You actually do not solely need to use it for tests, you can use it anywhere, but it's mostly useful for tests.

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• output-files

  1 5 5.2 JavaScript

  Output a tree of files and directories by providing an object. Especially useful for testing with real files.

I also wrote another helper package output-files that creates a whole file tree at once by passing an object. It's much easier than writing a lot of fs.writeFile calls to create many files.

• mocha

  138 22,421 7.6 JavaScript

  ☕️ simple, flexible, fun javascript test framework for node.js & the browser

  

Alright, let's dive into it! First of all you need a testing framework. I'm going to use Mocha here, but you can also use Jest or any other framework of your choice. I'm also using expect for assertions. After that, we'll install some packages that we need to write our tests:

• jest

  473 43,581 9.5 TypeScript

  Delightful JavaScript Testing.

  

Alright, let's dive into it! First of all you need a testing framework. I'm going to use Mocha here, but you can also use Jest or any other framework of your choice. I'm also using expect for assertions. After that, we'll install some packages that we need to write our tests:

• expect

  2 2,290 0.0 JavaScript

  Write better assertions

Alright, let's dive into it! First of all you need a testing framework. I'm going to use Mocha here, but you can also use Jest or any other framework of your choice. I'm also using expect for assertions. After that, we'll install some packages that we need to write our tests:

• fs-extra

  16 9,347 5.6 JavaScript

  Node.js: extra methods for the fs object like copy(), remove(), mkdirs()

fs-extra to read files after running the scaffolding tool.

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• endent

  1 12 2.6 TypeScript

  ⬅️ An ES6 string tag makes indentation better

endent to declare multi-line strings.

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