express-and-testing-workshop

A Founders and Coders workshop to teach testing and express backend connected to a PostgresSQL DB.

Learning Outcomes

• Add Tests to an express backend server/API
• Integration testing
• Learn to add tests to Express JS Routes - testing that routes work as expected and return what is expected

Introduction

• Express routes can be tested using TDD, to create a route in express you use express.Router.
• This is then added to the server as follows

// In Routes.js
router.get('/', (res, req) => {
  //Do Stuff
})
// In Server.js
const app = express()
app.use(routes)

• In this workshop you will find a server and database folder, which have been set up for you, so you should not have to change any code in these folders but feel free to have a look.

• The objective of this workshop is to write integration tests for a backend server which has already been setup.

• 'Integration tests' are tests that check the correct functioning of several interconnected functions all working together.

• Supertest and Tape allow us to perform Integration tests checking that the Server and Database are communicating properly, and calls to the Server endpoints respond with the correct status codes and any data requested.

• In the server folder there is a routes subfolder inside of which all the servers routes have been written for you (using promises).

• Your tests will ensure that not only these functions but also the database queries they depend on all work together to provide the information from each endpoint

Requirements

• Postman is a tool which allows you to test api endpoints to see what these return.
• An alternative is that you can use curl a command line took to ping an endpoint for example

   curl http://www.example.org:1234/

  to check each endpoint (though this is slighty more involved and I recommend downloading postman).

List of Endpoints

• /facsters
• /facsters/:name e.g. facsters/amelie
• /facster/new - This is a post request expecting an object
• /facsters/:name/superpower
• /facsters/:name/hobby

Tasks

• git clone this repository, run npm install.
• Set up the database:
  • Run createdb fac-express
  • Run psql or pgcli to enter the pg interactive terminal.
  • Enter CREATE USER super WITH SUPERUSER PASSWORD 'password';
  • Enter \q in psql or pgcli to leave the pg interactive terminal.
  • Run npm run build:db
• Run npm start. Now you can use postman or another tool to make requests to the endpoints.
• In another terminal pane run npm test.
• Then go to you test folder, and open routes.test.js
• Inside this file you will be using tape and supertest(a testing framework - link to the docs!!)
• Tape allows you to make assertions and check that things are equal etc. supertest will allow you to make requests to your server and expect certain results, and also has some limited assertion/testing functionality.
• The structure of your tests should be as below. Note that supertest is assigned to request as this is a convention.

  const test = require('tape')
  
  test('What your tests is testing', (t) => {
      request(app)
        .get('/facsters')
        .expect(200)
        .end(function(err, res) {
          /* INSERT TAPE TESTS HERE
          Don't forget to end your test */
        })
      })

Notes / Tips

• What should you test?
  • Think about what response you would want from the API and see if you can test that.
  • For example, you might test the status code (as above), the content type, and the contents of the body.
  • Make sure you write tests for each route, and test each response thoroughly.
• Although supertest is new to you there is a whole wide world of frameworks and libraries in javascript (#JSFatigue) and learning to use the docs is probably half of what it means to be a good js developer.
• You will note that I have snuck promises into this workshop as they are an extremely common and important tool for handling asynchronicity and are well on their way to replacing callbacks.
• you won't be expected to use these but I have used then to make the queries so take a look, please ask if any of it is unclear.