Update test firefox instructions to only refer to the yarn scripts

Author: clarkbw

shells/firefox/build.js

@@ -11,7 +11,7 @@ const {join} = require('path');
 const build = require('../webextension/build');
 
 const main = async () => {
- const unpackedPath = await build(
+ await build(
  'firefox',
  join(__dirname, 'manifest.json'),
  join(__dirname, 'build')
@@ -20,18 +20,13 @@ const main = async () => {
  console.log(chalk.green('\nThe Firefox extension has been built!'));
  console.log(chalk.green('You can test this build by running:'));
  console.log(chalk.gray('\n# From the react-devtools root directory:'));
- console.log('npm run test:firefox');
- console.log(chalk.green('\nYou can also test by following the steps below:'));
- console.log(chalk.gray('\n# Go to the unpacked directory:'));
- console.log(`cd ${unpackedPath}`);
- console.log(chalk.gray('\n# And launch Firefox with the extension enabled:'));
- console.log('yarn run start:firefox');
+ console.log('yarn run test:firefox');
  console.log(chalk.gray('\n# You can also test against upcoming Firefox releases.'));
  console.log(chalk.gray('# First download a release from https://www.mozilla.org/en-US/firefox/channel/desktop/'));
- console.log(chalk.gray('# And then tell web-ext which release to use (eg nigthly, beta):'));
- console.log('yarn run start:firefox -- --firefox=beta');
+ console.log(chalk.gray('# And then tell web-ext which release to use (eg firefoxdeveloperedition, nigthly, beta):'));
+ console.log('WEB_EXT_FIREFOX=nightly yarn run test:firefox');
  console.log(chalk.gray('\n# You can test against older versions too:'));
- console.log('yarn run start:firefox -- --firefox=/Applications/Firefox52.app/Contents/MacOS/firefox-bin');
+ console.log('WEB_EXT_FIREFOX=/Applications/Firefox52.app/Contents/MacOS/firefox-bin yarn run test:firefox');
 };
 
 main();