Automate tasks in OSS in 5 mins

Automate tasks in OSS in 5 mins

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What is danger.js anyway?

DangerJS runs during your CI process, and helps your team to automate certain manual code review tasks such as

  1. Is there a new library or module installed?
  2. Does this PR changes are added to changelog file?
  3. Is .lockfile kept up to date?
  4. Will this change increase my bundle size?

Example from ReactJS PR:

DangerJS in React

Let's integrate Danger.js in Github and Travis CI/CD services. This is a two step process.

Step 1:

Now let's add dangerjs to your devDependencies in package.json file.

yarn add danger -D

Step 2:

Then create dangerfile.js file on root of your project.


// Import the feedback functions
import { message, warn, fail, markdown } from 'danger';

// Add a message to the table
message('You have added 2 more modules to the app');

//  Adds a warning to the table
warn('You have not included a CHANGELOG entry.');

// Declares a blocking
fail(`ESLint has failed with ${fails} fails.`);

// Show markdown under the table:
markdown('## New module Danger' + dangerYarnInfo);

Step 3 (Optional):

This is an optional step, create an github account for your bot.

Step 4:

Create a New personal access token in github for read & write access for your bot.

Github Settings Page screenshot:

Github Settings Page

Step 5 (Final Step):

Finally, lets Hook danger.js in Travis CI

  • Copy the generated personal token from your github or your bot account you created.
  • Go to your project settings in Travis CI.
  • Create a new environment variable called DANGER_GITHUB_API_TOKEN and the value is your personal token.

Travis Settings Page screenshot:

Travis Settings Page

After this step, you should be seeing bot account adding comments to your every PR as per your dangerfile.js config.

Example from QR Code Scanner PR:

Code Kotis - QR Code Scanner

Test it locally:

You can test your changes locally using following terminal command.

yarn danger pr <your-pr-link>

Final note:

By adding danger.js will help us save time in OSS project by automating mundane tasks. Thank you for reading my post till the end. If you like my post share it 😇.

  • ReactJS dangerfile.
  • Tutorials for other app such as node app, node libraries etc.

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