{"id":11085,"date":"2018-03-01T09:49:56","date_gmt":"2018-03-01T08:49:56","guid":{"rendered":"http:\/\/flaven.fr\/?p=11085"},"modified":"2026-09-16T10:10:21","modified_gmt":"2026-09-16T08:10:21","slug":"api-postman-newman-create-a-quick-api-with-json-server-and-faker-and-then-test-it-with-chai-js-postman-and-newman","status":"publish","type":"post","link":"https:\/\/flaven.fr\/2018\/03\/api-postman-newman-create-a-quick-api-with-json-server-and-faker-and-then-test-it-with-chai-js-postman-and-newman\/","title":{"rendered":"API, Postman, Newman – Create a quick API with json-server and Faker and then test it with Chai-JS, Postman and Newman"},"content":{"rendered":"

It is true I have given a title to this post that sounds like a user story of somebody who want to make name dropping. In a sense, it is true but it is for SEO purpose. The story behind is absolutely genuine : I wanted to explore testing on an API with the help of Postman and Chai! But as usual, this question is followed by another one: what API can I test? Some posts quoted below goes for an existing API such as Twitter for instance. As one thing led to another, I have decided to first build an API with the help of json-server and faker and then test this freshly born API with Chai-JS, Postman. I added at the very end Newman, just to have the cool triptych, a kind of holy trinity of API testing \ud83d\ude42<\/p>\n

The code is on github @https:\/\/github.com\/bflaven\/BlogArticlesExamples\/tree\/master\/to-test-a-mockingapi<\/a><\/b><\/p>\n

Build your API<\/h3>\n

I found the easiest way to build-up an API with json-server. It is straight forward, the downside is that API is very primitive.<\/p>\n

The idea is to installed json-server and create a dir for you API, then you create a json file that will “host” the datas. In my case, the file is called users_russian.json. <\/p>\n

The fun part came with the usage of Faker, it is always fun to generate fake content especially in foreign language. I have decided to go for Russian.<\/p>\n

1. Just to install json-server<\/b><\/p>\n

npm install -g json-server<\/pre>\n
2. Create a directory for your future API. Mine is called to-test-a-mockingapi<\/b><\/p>\n
mkdir to-test-a-mockingapi<\/pre>\n
3. Get in the directory<\/b><\/p>\n
cd \/[to-your-dir]\/to-test-a-mockingapi<\/pre>\n
4. Create a json file. Mine is users_russian.json<\/b><\/p>\n
touch users_russian.json<\/pre>\n
5. Add one line to users_russian.json<\/b><\/p>\n
\r\n\t{\r\n  \"users\": [\r\n    { \"id\": 1, \"first_name\": \"\u041b\u0443\u043a\u0430\", \"last_name\": \"\u0421\u043e\u043b\u043e\u0432\u044c\u0435\u0432\",  \"city\": \"\u041d\u0430\u0442\u0430\u043b\u044c\u044fport\", \"email\": \"\u0421\u043e\u043b\u043e51@hotmail.com\" }\r\n  ]\r\n}\r\n<\/pre>\n
6. To load the json into the json server:<\/b><\/p>\n
json-server users_russian.json<\/pre>\n
After these 6 steps, you have a fully functional API, able to make basic CRUD operations (Create, Read, Update, and Delete)<\/b><\/p>\n
Let’s have fun with Faker<\/h3>\n
The idea is to generate a lot a fake content : first to avoid implementing real data,  second avoid manually populating data in your API, this is exhausting.<\/p>\n
Install faker to generate fake content<\/b><\/p>\n
npm install faker<\/pre>\n
Generate fake content in Russian<\/b><\/p>\n
node users_russian.js<\/pre>\n
Generate fake content in Russian into a json file that will be loaded in json-server<\/b><\/p>\n
node users_russian.js > users_russian.json<\/pre>\n
The content of JS script for node, users_russian.js<\/b><\/p>\n
\r\n\/\/  users_russian.js\r\n\r\nvar faker = require('faker');\r\n\r\n\/*\r\nCheck https:\/\/github.com\/marak\/Faker.js\/ for Localization\r\n*\/\r\n\/\/ sets locale\r\n\/\/ faker.locale = \"ru\" \/\/ (Russian)\r\n\/\/ faker.locale = \"pt_BR\" \/\/ (Portugu\u00eas do Brasil)\r\n\/\/ faker.locale = \"it\" \/\/ (Italian)\r\n\/\/ faker.locale = \"fr\" \/\/ (French)\r\n\/\/ faker.locale = \"es\" \/\/ (Spanish)\r\n\r\n\r\nfaker.locale = \"ru\"; \/\/ (Russian)\r\n\r\nvar db = { users: [] };\r\n\r\nfor (var i=1; i<=1000; i++) {\r\n  db.users.push({\r\n            id: i,\r\n            first_name: faker.name.firstName(),\r\n            last_name: faker.name.lastName(),\r\n            city: faker.address.city(),\r\n            email: faker.internet.email()\r\n  });\r\n}\r\nconsole.log(JSON.stringify(db));\r\n<\/pre>\n
The CRUD actions are still working but you have much more records...<\/b><\/p>\n
POST in postman<\/b><\/p>\n
{\"id\": 1001, \"first_name\": \"\u0422\u0430\u0442\u044c\u044f\u043d\u0430\", \"last_name\": \"\u0421\u0430\u0444\u043e\u043d\u043e\u0432\u0430\", \"city\": \"\u041a\u0443\u0437\u044c\u043c\u0438\u043dside\", \"email\": \"\u0422\u0430\u0442\u044c\u044f\u043d\u043081@gmail.com\"}<\/pre>\n
PUT in postman for http:\/\/localhost:3000\/users\/1001<\/b><\/p>\n
{\"id\": 1001, \"first_name\": \"\u041d\u0438\u043a\u0438\u0442\u0430\", \"last_name\": \"\u042e\u0434\u0438\u043d\u0430\", \"city\": \"New \u041b\u0430\u0440\u0438\u0441\u0430\", \"email\": \"\u041d\u0438\u043a\u0438\u0442\u0430_40@yahoo.com\"}<\/pre>\n
Sample of Russian users made with Faker<\/b>
\n\"API,<\/p>\n
Start json-server with users_russian.json<\/b>
\n\"API,<\/p>\n
Show me the fresh API in a browser<\/b>
\n\"API,<\/p>\n
Show me the fresh API in a Postman<\/b>
\n\"API,<\/p>\n
The CRUD operations: GET one record of the API via Postman<\/b>
\n\"API,<\/p>\n
The CRUD operations: POST one record of the API via Postman<\/b>
\n\"API,<\/p>\n
The CRUD operations: DELETE one record of the API via Postman<\/b>
\n\"API,<\/p>\n
The CRUD operations: PUT (update) one record of the API via Postman<\/b>
\n\"API,<\/p>\n
Check the activity of the json-server via the console<\/b>
\n\"API,<\/p>\n
You have fully functional API with all the CRUD operations. Let's make some test now with Chai.<\/p>\n
Test with Chai<\/h3>\n
You need to create an development environment (DEV ENV) in Postman. Very easy, just enter this variable and make the query the first of your test.<\/p>\n
I have called the DEV ENV postman_bdd_env<\/code><\/b><\/p>\n
postman_bdd_path: http:\/\/bigstickcarpet.com\/postman-bdd\/dist\/postman-bdd.min.js<\/pre>\n
Source : https:\/\/www.npmjs.com\/package\/postman-bdd<\/a><\/p>\n
Writing tests with Postman BDD. This is made with Chai-JS.<\/b>
\n\"API,<\/p>\n
Integration with Newman<\/h3>\n
You need to install newman first, choose to install globally.<\/p>\n
npm install newman --global<\/pre>\n
Quickly, here what they say about Newman, I just quote.<\/p>\n
Postman has a command-line test runner called Newman. If you prefer the CLI instead of a GUI, then this the tool for you. It's also ideal for continuous-integration and continuous-delivery testing. Just like the Collection Runner, you can run your entire suite of tests, or just a single folder. You can load data from a file, and even write the test results to an output file in various formats (JSON, XML, HTML).<\/p><\/blockquote>\n
Source : https:\/\/github.com\/BigstickCarpet\/postman-bdd<\/a><\/p>\n
When you have exported your collection, just run this command. My collection is called russian_roulette.postman_collection.json<\/code><\/b><\/p>\n
newman run russian_roulette.postman_collection.json<\/pre>\n
Launching a test collection (russian_roulette.postman_collection.json) via Newman. It fails!<\/b>
\n\"API,<\/p>\n
To proper launch your tests collection (russian_roulette.postman_collection.json), you need to make a first call to {{postman_bdd_path}} aka postman-bdd.min.js<\/b>
\n\"API,<\/p>\n
Launching a test collection (russian_roulette.postman_collection.json) via Newman after the correction. It works!<\/b>
\n\"API,<\/p>\n
Conclusion : Very useful and promising for anyone who dare to develop an API and remember little grasshopper \"to test is to doubt\".<\/b><\/p>\n
Read more<\/h2>\n