mocha-vite-puppeteer

Run your Mocha front-end tests with the Vite bundler and the Puppeteer browser launcher.

"mocha-vite-puppeteer" can be used with any existing Vite project and is not specific to Vue, React or any other front-end library. Both JavaScript and TypeScript is supported via Vite.

Install

npm install mocha-vite-puppeteer

Run

First add some test files using Mocha, e.g. Counter.test.jsx:

import { expect } from "chai";
import React from "react";
import { render, screen } from "@testing-library/react";

import Counter from "./Counter";

describe("Counter", () => {
  it("should count", () => {
    render(<Counter />);
    const countButton = screen.getByText("count is: 0");
    countButton.click();
    screen.getByText("count is: 1");
  });
});

Remember to add any additional dependencies used by the tests, in this case:

$ npm install chai @testing-library/react

Note: "mocha-vite-puppeteer" is not React specific, and should work just as well with Vue, Preact or any other front-end library supported by Vite.

Then run your tests, bundled with Vite, in Puppeteer with:

$ npx mocha-vite-puppeteer

You will see output similar to:

  Counter
    ✓ should count
  1 passing (24ms)

An exit code of 0 indicates that all tests passes. In general, the exit code indicates the number of failed tests, which can be used in CI pipelines.

For now the following built-in reporters are supported:

dot
json
json-stream
list
spec
tap

And also the following custom reporter is supported:

mocha-junit-reporter

You can optionally specify a JSON file with reporter options:

$ npx mocha-vite-puppeteer --reporter mocha-junit-reporter --reporter-options mocha-junit-reporter.config.json

By default mocha-vite-puppeteer will create a default "test.html" to configure mocha and load your test-files. But you can also write your own test.html placed next to index.html. Here is an example:

<!DOCTYPE html>
<html lang="en">
  <body>
    <script type="module" src="/mocha-setup.js"></script>
    <script type="module" src="/test-loader.js"></script>
  </body>
</html>

mocha-setup.js:

import "mocha";
mocha.setup({ ui: "bdd" });

test-loader.js:

const modules = import.meta.globEager("/src/**/*.test.{js,jsx}");

Available Flags

Flag	Alias	Default	Description
--port	-p	3001	Sets the port for Mocha-Vite-Puppeteer to run on
--entry	-e	'test.html'	Entry html file that initializes Mocha. Relative to cwd
--reporter	-r	'spec'	Reporter to use for mocha tests
--reporterOptions	-o	undefined	reporter options file to be passed to reporter
--verbose	-v	false	Enables verbose reporting from Mocha-Vite-Puppeteer. Useful for debugging these flags and inputs.
--debug	-d	false	Sets debug mode for Mocha-Vite-Puppeteer. Automatically disabled puppeteer headless mode.
--config	-c	undefined	Advanced config options. See section below for details
--enableBarePath		true	Load entry html file from "/" (html file cannot use inline script of type "module")
--coverage		false	Instrument and collect code coverage during test. Use "nyc" for reporting

Advanced Configuration

{
  "port": 3010,
  "reporter": "dot",
  "coverage": true,
  "puppeteer": {
    "launchOptions": {
      "headless": false,
      ...
    }
  },
  "istanbul": {
    "include": ["src/*"]
  }
}

The base-level of the object accepts any flag above, except config of course.

The key "puppeteer" can be used for additional puppeteer configuration. The puppeteer currently only accepts the key launchOptions. see the puppeteer docs on launch options for a full list of launch options available.

The key "istanbul" can be used for additional code coverage configuration, see the section on Code Coverage below.

Code coverage

When using the --coverage option, a raw coverage report is produced in a .nyc_output folder. To get a nicely formatted report, you will have to use the nyc CLI, such as:

nyc report --reporter=text-summary --reporter=html --exclude-after-remap false

Instrumentation for coverage analysis is handled by vite-plugin-istanbul. Any options needed for your project to work with this plugin can be added via the mocha-vite-puppeteer config file under the "istanbul" key, see Advanced configuration above.

The --exclude-after-remap false option for nyc is needed because vite handle all transpilation (JSX, TypeScript etc) pre-instrumentation.

Develop

Use bash or similar (such as Git Bash on Windows).

npm test

Contributions welcome!

Publish

npm version minor
npm publish
git push

larsthorup/mocha-vite-puppeteer