To add Mocha/Chai/Sinon beside Jest in an official Aurelia v1's Jest/Cypress template so follow below steps:

1. Change current configs to make it possible to add Mocha beside it.

   • Rename test/unit folder to test/unit-jest.
   • Change Options.relativeToDir = path.join(__dirname, 'unit'); line inside test\jest-pretest.ts to Options.relativeToDir = path.join(__dirname, 'unit-jest');.
   • Change "test": "au test", inside package.json to "test-jest": "au test",.

2. Create a clone of tsconfig.json with name of tsconfig.mocha-test.json in root directory with these new changes

"module": "commonjs",
"target": "es6",

3. Add the below config to to the package.json file and jest section.

"jest": {

    "roots": [
      "./test/unit-jest"
    ],
	
}	

4. Install the below packages

npm install -D ts-node mocha chai sinon nyc @types/mocha @types/chai @types/sinon
yarn add -D ts-node mocha chai sinon nyc @types/mocha @types/chai @types/sinon

5. Create a new folder for Mocha tests test/unit-mocha.

6. Create .mocharc.js file in root directory with the following content

'use strict'

module.exports = {  
  exit: true,
  timeout: '3000',
  recursive: true,
  file: ['./test/mocha-pretest.js'],
  spec: "test/unit-mocha/**/*.ts"
}

7. Create mocha-pretest.js inside test folder. (Should be .js)

require("ts-node").register({
  project: "tsconfig.mocha-test.json",
});

8. To use Istanbul (nyc) coverage tool with Mocha, we need to add new nyc section into the package.json.

"nyc": {
  "extension": [
    ".ts",
    ".tsx"
  ],
  "include": "src",
  "exclude": [
    "**/*.d.ts"
  ],
  "reporter": [
    "html",
    "text"
  ],
  "all": true,
  "report-dir": "test/coverage-mocha"
}

9. Add the following command to package.json file and scripts section.

"test": "node_modules/.bin/nyc mocha"

Although, you can separate the test and coverage like the following:

"test": "node_modules/.bin/mocha"
"coverage": "node_modules/.bin/nyc mocha"

Now, the coverage test result will be available under test/coverage-mocha directory.

10. Just like the Jest version, create a new app.spec.ts file for testing inside the test/unit-mocha directory.

import {App} from '../../src/app';
import { expect } from "chai";

describe('the app', () => {
  it('says hello', () => {
    expect(new App().message).to.equal('Hello World!');
  });
});

Tip: Maybe you see some TypeScript errors in your project, so, add the following configs to your main TypeScript configuration (tsconfig.json).

"exclude": [ "test/coverage-jest", "test/coverage-mocha", "test/mocha-pretest.js" ],

and also check do you have the iterable config for working with Cypress without problem or not.

"lib": [
    // ...
    "es2015.iterable",
    // ...
],