Testing Node with TDD

Project setup

  1. Initiate projects
    1. Open your terminal and navigate to your desired project-folder
    2. Run command: npm init

    This will create a package.json file with the basic information.

    1. Install your dependencies:
      • Express
      • Mocha
      • Chai
      • Supertest

      Look into the documentation for theses packages. We will use Express to create a simple webserver and routing for our app. We will use Mocha as a testing framework and add Chai to have some extra assertion-options like should and expect. To create integration tests against our webserver we will use Supertest.

  2. Setup testing environment
    1. open package.json and add “mocha” to the test-field
    2. In the project root, add a folder named “test”
    3. In the test folder, add your first test-file named index.ITest.js

Write tests and implement express routes

In this first example you shall now write an integration test for an expected endpoint

  1. /api/persons
describe("Test api endpoints", () => {
	it("/api/persons", () => {
		return request(app)
		.get("/api/persons")
		.expect(200)
		.then(res => {
			expect(res.body.result).to.be.an("array");
			expect(res.body.result[0].name).to.exist;
			expect(res.body.result[0].age).to.exist;
			expect(res.body.result[0].email)to.not.be.undefined;
		});
	});
});

The first task is to get the test running, and make it fail. You will at the very least need to import mocha,chai, and supertest. If you struggle with the part of getting it running, have a look at the sample project in the “testing_node” folder.

You will see that in order to test the endpoint successfully, you should put it in a separate file called router.js. The reason for doing this is that it makes it easier to import the router in your index.ITest.js-file. Simpler modules are easier to test and reuse.

  1. When the tests fails successfully ;), we will go ahead and implement the express endpoint. To do this we will create an index.js file in the root of the project-folder. Use what you have learned in the project setup task to do this. The express-route may look something like this:
router.get('/persons', (req, res) => {
	res.json({result: persons});
});

The result of this route should be an object containing a list of persons

  1. Finally you should make two more tests and implement their endpoints based on the json-files in testing-node/data folder. You don’t have to test for everything, choose what you think is important.

Using tests in your Portfolio-project

By now you are probably a bit more familiar with the concept of testing. The tests you have written so far is a kind of integration test meant to check that the endpoints are made to a specification and that they keep their expected functionality when you develop the application further.