Validating code Architecture with dependency cruiser

We are going to use dependency cruiser.

In this short tutorial we are going to create a custom rule that makes sure that your controller files cannot import your repositories. The rules can be a lot more ellaborate. The idea is to showcase that it is easy and that it doesn’t need to take a lot of time to get the automatic checks going.

Create an npm project, install ts-node, dependency cruiser, etc.

Then, initialize our dependencies:

npx depcruise --init

npx tsc --init

We are going to create two files asd.repository.ts and hello.controller.ts.

Create our test files. They should be in the root directory.

//asd.repository.ts

function asd() { return 12; }

export default asd;

Create our test files. They should be in the root directory.

//hello.controller.ts

import asd from "./asd.repository";

asd();

In our scenario hello.controller.ts violates our architecture rules! Controllers must not use repositories directly. So how can we write a rule that fixes it ?

We need to edit the dependency-cruiser configuration file. It is already generated and should be in the root level of your project: .dependency-cruiser.js

We need to edit the rules array inside and add a new object.

The object we are going to add is:

{ name: "no-controller-using-repository", from: { path: "controller" }, to: { path: "repository" }, },

… And that is all there is to it! Now any file containing repository in it’s name can’t be used by a file containing controller in it’s name.

Let’s test it out:

npx depcruise . --config

Will produce the following output: