Mocha Chai Assert

Assert/Mocha/Chai/Cypress Libraries: Tools/Libraries and modules used to write unit tests on applications.

Mocha: Library of code that runs the tests (installed already on Cypress) Chai: The assertion Library for Mocha (installed already on Cypress) Assert: default assertion library for Node.js

Mocha/Chai/Assert Example test describe block: describe("#combine", () => { it ("should combine two sets of item data", () => { assert.deepEqual(data.combine(dataSet1, dataSet2), combinedResult) }); });

Setup/Installation:

Note: The package.json file must have “mocha” as the “test” under “scripts”. Note: The package.json file must have “chai” and “mocha” under the devDependencies.

The data.js file contains: The data that is in the file and the functions that are to be tested. The module.exports are listed at the bottom of the file.

The data.test.js file contains: // asserts at the top of the file. // create the data that is to be tested // create the describe/it testing blocks

const assert = require(“assert”); ← to use the node assert library const assert = require(“chai”).assert ← to use chai after installing const data = require(“../data”); ← the data file

How to set up Unit testing with Mocha/Chai/Assert:

1. Create a node project npm init || npm init -y
2. Install your testing dependencies npm install mocha chai --save-dev
3. Create a directory called test

• Create a file name-of-js-file.test.js

4. Change the test script to run mocha

• In your package.json "test": "mocha"

5. Create a variable named assert and require your preferred assertion library
6. Write your describe and it blocks
7. Write your assertion statements

• Ensure you are pulling in your code using module.exports

8. Run your tests! Red, Green, Refactor!