hello_jest A hello world example of testing javascript using Jest

This repository is intended to provide a relatively simple and minimal example of Javascript testing and code coverage for a client side Javascript module, specifically for jQuery plugins.

I hope people (like me) find it helpful when they want to create npm modules with automated testing and coverage reports.

To enable continuous integration and code coverage evaluation I registered this repository with the Travis CI service and the coveralls coverage service.

What are the files?

Here are the files used in the package In some cases they are copied from other places and I don't understand fully their significance, but I needed them to get everything working.

hello_jest/src/my_plugin.js

This is a silly jQuery plugin implementation which is supposed to represent the main logic of the module that we want to test and publish.

hello_jest/src/index.js

This is the module index file used by npm for creating the module package. It lists everything which should be included in the module.

hello_jest/package.json

This is the npm package description for the module. It describes how to build, test, and package the module and the module top level dependencies and so forth.

hello_jest/jest.config.js

This is the jest configuration file. It describes the test environment (such as environment globals) and where to put the coverage report, among other things.

hello_jest/.travis.yml

This file tells the Travis continuous integration service how to run the tests and register the coverage report.

hello_jest/.babelrc

This file tells the babel preprocessor how to translate javascript.

Background

This repository is built

• Using https://jestjs.io/ and
• with continuous integration using https://travis-ci.org/ and
• with code coverage for unit tests using mocking.

Eventually

I wanted to add

• with a headless browser https://github.com/GoogleChrome/puppeteer for end to end tests.

But I'm giving up on that for now. Maybe later I will return.

References

• Trying to follow: https://medium.com/@ollelauribostr/start-measuring-coverage-with-jest-travis-ci-and-coveralls-1867928aca42
• Stealing the basic structure of the project: https://blog.npmjs.org/post/112064849860/using-jquery-plugins-with-npm
• And using more information from: https://medium.com/piecesofcode/testing-javascript-code-with-jest-18a398888838
• Mimicking https://github.com/xfumihiro/jest-puppeteer-example
• https://www.valentinog.com/blog/ui-testing-jest-puppetteer/
• https://medium.com/@ollelauribostr/start-measuring-coverage-with-jest-travis-ci-and-coveralls-1867928aca42
• https://github.com/ollelauribostrom/travis-coveralls-example
• https://coveralls.io/github/ollelauribostrom/travis-coveralls-example
• https://blog.npmjs.org/post/111475741445/publishing-your-jquery-plugin-to-npm-the-quick
• https://docs.npmjs.com/cli/link npm link for creating a local link to a package.
• https://jaketrent.com/post/npm-install-local-files/ using tarballs.

Setting up jest with puppeteer example:

  374  git clone https://github.com/xfumihiro/jest-puppeteer-example.git
  376  cd jest-puppeteer-example/
  377  node install
  382  npm install yarn -g
  384  yarn add jest-puppeteer
  390  npm install jest -g
  391  jest