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https://github.com/kkgthb/web-site-nodejs-02-tests
Code for a teeny-tiny Node.js web server with Jest unit tests to ensure it really says Hello World!
https://github.com/kkgthb/web-site-nodejs-02-tests
express-js expressjs jest jest-tests node-js nodejs unit-testing web-server webserver
Last synced: 8 days ago
JSON representation
Code for a teeny-tiny Node.js web server with Jest unit tests to ensure it really says Hello World!
- Host: GitHub
- URL: https://github.com/kkgthb/web-site-nodejs-02-tests
- Owner: kkgthb
- Created: 2023-03-16T21:23:06.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2023-03-16T21:39:51.000Z (almost 2 years ago)
- Last Synced: 2024-11-09T06:25:11.290Z (2 months ago)
- Topics: express-js, expressjs, jest, jest-tests, node-js, nodejs, unit-testing, web-server, webserver
- Language: JavaScript
- Homepage: https://katiekodes.com/node-unit-test-jest/
- Size: 6.84 KB
- Stars: 1
- Watchers: 1
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# A tiny _testable_ Node.js website
(Accompanies associated blog post on Katie Kodes "[Locally unit-testing source code for a Node.js Hello World webapp](https://katiekodes.com/node-unit-test-jest/)".)
---
## Prerequisites
1. Please work your way through my entire exercise "[Source code that builds locally into a Node.js Hello World webapp](https://katiekodes.com/node-hello-world/)" before beginning this exercise so that you're familiar with "building" and "running" a webserver _(although in this case, we won't do either of those things -- instead we'll be "testing" it)_ from source code.
1. As mentioned there, you need to have Node.js installed and NPM installed onto your local computer.
1. Download a copy of **this** codebase onto your local computer, being sure to give it a completely _different_ folder from the one you used for the previous exercise.
1. Using a command line interface -- ensuring first that its prompt indicates that your commands will be running within the context of the folder into which you downloaded a copy of **this** -- you must run the following command:
```sh
npm install
```
The `npm install` command will take about a minute to execute.
It will add a new subfolder and a new file to the folder on your computer containing a copy of this codebase:
1. A `/node_modules/` folder _(important, and note that its contents will be different than in the last exercise)_.
2. A `/package-lock.json` file _(unnecessary for this exercise but not hurting anything)_.
---
## Running tests that pass
Open up a command line interface.
Ensure that its prompt indicates that your commands will be running within the context of the folder into which you downloaded a copy of this codebase.
Run the following command:
```sh
npm run test
```
The output you will see will say something like:
```
> test
> cross-env NODE_ENV=test jest --testTimeout=10000 --detectOpenHandles
PASS src/__tests__/my-first-test.js
Homepage Hello
√ GET / return hello world (135 ms)
√ GET /index.html return hello world (16 ms)
Test Suites: 1 passed, 1 total
Tests: 2 passed, 2 total
Snapshots: 0 total
Time: 1.261 s, estimated 2 s
Ran all test suites.
```
---
## Running tests that fail
Edit the contents of line 12 of the file at `/src/__tests__/my-first-test.js` and replace the word "**World**" with the word "**Goodbye**" so that instead of looking for `"Hello World!"` your test is looking for `"Hello Goodbye!"`.
Open up a command line interface.
Ensure that its prompt indicates that your commands will be running within the context of the folder into which you downloaded a copy of this codebase.
Run the following command:
```sh
npm run test
```
The output you will see will say something like this, complaining that the homepage, both when accessed as `http://localhost:3000/` and as `http://localhost:3000/index.html`, says "**Hello World**" instead of saying "**Hello Goodbye** as expected by the unit test _(after all, you just finished turning your unit test into a [Beatles fan](https://en.wikipedia.org/wiki/Hello,_Goodbye))_:
```
> test
> cross-env NODE_ENV=test jest --testTimeout=10000 --detectOpenHandles
FAIL src/__tests__/my-first-test.js
Homepage Hello
× GET / return hello world (146 ms)
× GET /index.html return hello world (20 ms)
● Homepage Hello › GET / return hello world
expect(received).toEqual(expected) // deep equality
Expected: "Hello Goodbye!"
Received: "Hello World!"
10 | expect(supertest_response.status).toEqual(200);
11 | expect(supertest_response.type).toEqual('text/html');
> 12 | expect(supertest_response.text).toEqual("Hello Goodbye!");
| ^
13 | }
14 | it("GET / return hello world", async () => {
15 | const res = await supertest(my_express_server).get("/");
at toEqual (src/__tests__/my-first-test.js:12:41)
at Object.check_homepage_expectations (src/__tests__/my-first-test.js:16:9)
● Homepage Hello › GET /index.html return hello world
expect(received).toEqual(expected) // deep equality
Expected: "Hello Goodbye!"
Received: "Hello World!"
10 | expect(supertest_response.status).toEqual(200);
11 | expect(supertest_response.type).toEqual('text/html');
> 12 | expect(supertest_response.text).toEqual("Hello Goodbye!");
| ^
13 | }
14 | it("GET / return hello world", async () => {
15 | const res = await supertest(my_express_server).get("/");
at toEqual (src/__tests__/my-first-test.js:12:41)
at Object.check_homepage_expectations (src/__tests__/my-first-test.js:20:9)
Test Suites: 1 failed, 1 total
Tests: 2 failed, 2 total
Snapshots: 0 total
Time: 1.495 s, estimated 2 s
Ran all test suites.
```
---
## Anxious? Go ahead and let the test pass again
P.S. If leaving a failing test lying around is really bothering you, feel free to either:
1. Change "`Goodbye`" back to "`World`," or
2. Engage in some "[test-driven-development](https://en.wikipedia.org/wiki/Test-driven_development)" _("TDD")_ by updating line 6 of `/src/web/server.js` from "`World`" to "`Goodbye`."
Then run `npm run test` one more time to set your heart at ease.
---
## Extra credit -- build and run
You're not _forbidden_ from building and running this server just because it's not the focus of this exercise.
Go ahead -- try `npm run build` and then `node ./dist/server.js` against this codebase just like you did against the last one.
In fact, try it with the server saying "`World`" and the test expecting "`Goodbye`."
Did you notice that nothing at all goes wrong with the build process or with visiting your website on `localhost`?
_(Although when you visit it, it will say "`World`," not "`Goodbye`" -- remember, that's what you told the server to do.)_
By **deliberately** running `npm run build` and `node ./dist/server.js` even when you _knew_ that `npm run test` would be angry with you, you've arguably "built" a runtime out of "bad code" and chosen to run "bad code" on a webserver.
Luckily, you've only done so on your local machine, but as we work our way through this series, we'll make sure to build codebases and habits that prevent us from running `npm run build` if `npm run test` failed.