Testing

NON-automated testing

Click around and try things yourself!
Manual testing (team): usually has a list of things to click through
User (research) testing: give users your site and let them click around

Automated Testing of Code

Definition: Automated tests are additional code that tests the code of a project
- This includes how things should go correctly AND incorrectly
Types of Tests
- Unit tests: test ONE thing
- Integration Tests: isolate and test code that calls other code, for example, is this code connecting to the db?
- System Tests/E2E Tests: test the overall system; E2E is the flow end-to-end, System is in the context of a prod-like environment
- Stress Tests: test what happens when parts of the system fail
Strategies:
- Running Tests: Continuous Integration Testing
- How do we know our tests are right?
  - Code Coverage
  - We don’t know (Skype/postmortems/rollbacks)
- Best practices:
  - When something breaks in prod, the fix should include a test that would have caught that change/error
  - CI/CD testing: on PR, if something new is broken, block merge

npm install --save-dev <package>

Installs the package as a development dependency.
Adds it to the "devDependencies" section in package.json.
Used when the package is only needed during development (e.g. for testing, building, or linting).

npm test run test in project

app.test.js

import { assert } from 'chai'
import request from 'supertest'

import app from '../app.js'

describe('Static server', () => {
    it('should return index.html if it is requested', async () => {
        const res = await request(app).get('/index.html')

        assert.equal(res.statusCode, 200)

        assert.include(
            res.text,
            '<script src="javascripts/index.js"></script>',
            "body has html code we recognize from index.html"
        )
    })

    it("should return 404 for a non-existing file", async() => {
        const res = await request(app).get("/fdmaifodamsf.html")
        assert.equal(res.statusCode, 404)
    })
})

example.test.js

import assert from 'assert'

describe('DemoTest', () => {
    it('should say 2+2 = 4', () => {
        assert.equal(2+2, 4)
    })

    it("should say 4+4 = 8", () => {
        assert.equal(4+4, 8)
    })

        it("should say 1+1 = 3", () => {
        assert.equal(1+1, 3)
    })
})

items.test.js

import { assert } from 'chai'
import request from 'supertest'

import app from '../app.js'

describe('Items integration test (with database)', () => {
    it('should get items from the db for GET items', async () => {
        const res = await request(app).get('/items')

        assert.equal(res.statusCode, 200)
        assert.equal(res.type, 'application/json')

        assert.isArray(res.body)
        assert.include(res.body[0], {
            name: "apple", 
            price: 2.99
        })
    })
})

package.json

{
  "name": "express-starter",
  "version": "0.0.0",
  "private": true,
  "type": "module",
  "scripts": {
    "start": "node ./bin/www",
    "test": "mocha"
  },
  "dependencies": {
    "cookie-parser": "~1.4.4",
    "debug": "~2.6.9",
    "express": "^4.19.2",
    "express-session": "^1.17.2",
    "mongoose": "^6.0.11",
    "morgan": "~1.9.1",
    "stripe": "^9.0.0"
  },
  "devDependencies": {
    "mocha": "^11.4.0"
  }
}