Test your PostCSS plugin with AVA and this handy tool.

// test.js
import test from 'ava';
import PostcssTester from 'ava-postcss-tester';

const tester = new PostcssTester({
  postcss: require('postcss'),
  plugin: require('.')
});

test('test name', async t => {
  const input = `
    .class {
      size: 100px;
    }
  `;
  const output = `
    .class {
      width: 100px;
      height: 100px;
    }
  `;
  await tester.test(input, output, t);
});

$ npm install -D ava-postcss-tester

Create a new tester by calling new PostcssTester with an options object:

• postcss: The postcss module to use for process
• plugin: You PostCSS plugin to test (can be an array of plugins) tolerateWarnings;
• from: Optional, default: '', The from parameter passed to postcss.process, must be a file path
• tolerateWarnings: Optional, default: false, Ignore PostCSS warnings
• exactComparaison: Optional, default: false, Compare the input and output without any trimming or line breaks cleaning

import test from 'ava';
import PostcssTester from 'ava-postcss-tester';

const tester = new PostcssTester({
  postcss: require('postcss'),
  plugin: require('.'),
  tolerateWarnings: true
});

Then you can run the async function `tester.test(input, output, t, options)``:

• input: A string containing your css input
• output: A string containing your excpected output, it can be either a CSS string, an Error or a function receiving (error, warnings, result) letting you finish the test as you would like it
  • error: A string containing the Error message
  • warnings: An array of PostCSS warnings, is null if there an error occured
  • result: A string containing the PostCSS process result
• t: The AVA test t object
• options: Optional, An object containing those additional parameters:
  • pluginOptions: Options passed to your plugin
  • pluginsBefore: An array of plugins to load before your plugin
  • pluginsAfter: An array of plugins to load after your plugin

test('test name', async t => {
  const input = `
    .class {
      size: 100px;
    }
  `;
  const output = `
    .class {
      width: 100px;
      height: 100px;
    }
  `;
  await tester.test(input, output, t, {
    pluginOptions: {
      sizeShorthandActivated: true
    },
    pluginsAfter: [require('autoprefixer')]
  });
});

• postcss - Transforming styles with JS plugins
• ava - Futuristic JavaScript test runner
• one-liner - Module used for comparing excepted and real CSS output

This project is licensed under the MIT license.