Merge pull request #24 from storybooks/simplified-yarn-support

Use a non-hacky way to detect yarn.

README.md

@@ -20,25 +20,17 @@ That's all you've to do.
 
 ---
 
-## Yarn support
+## [Yarn](https://github.com/yarnpkg/yarn) support
 
-getstorybook also supports yarn. If you are using yarn, this is how to use it:
+`getstorybook` also supports yarn.
+If you have installed yarn in your system, it'll detect it and use `yarn` instead of `npm`.
+
+If you don't want to use `npm` always you can use the `--use-npm` option like this:
 
 ```
-yarn global add getstorybook
-getstorybook --use-yarn
+getstorybook --use-npm
 ```
 
-`getstorybook` will identify it's installed with yarn and it'll use yarn to install deps.
-
-> This is the way, if you wanna use yarn for all of your storybook projects.
 
-If that's not the case, you can do this:
-
-```
-npm i -g getstorybook
-getstorybook --use-yarn
-
-```
 
 For more information, refer [React Storybook](https://github.com/kadirahq/react-storybook) documentation.

bin/generate.js

@@ -4,28 +4,29 @@
 
 var updateNotifier = require('update-notifier');
 var program = require('commander');
+var chalk = require('chalk');
 var detect = require('../lib/detect');
+var hasYarn = require('../lib/has_yarn')
 var types = require('../lib/project_types');
 var commandLog = require('../lib/helpers').commandLog;
 var codeLog = require('../lib/helpers').codeLog;
 var paddedLog = require('../lib/helpers').paddedLog;
 var installDeps = require('../lib/helpers').installDeps;
-var chalk = require('chalk');
 var logger = console;
 
 var pkg = require('../package.json');
 
 program
   .version(pkg.version)
   .option('-f --force', 'Forcely add storybook')
-  .option('-Y --use-yarn', 'Use yarn to install deps')
+  .option('-N --use-npm', 'Use npm to install deps')
   .parse(process.argv);
 
 var welcomeMessage =
   'getstorybook - the simplest way to add a storybook to your project.';
 logger.log(chalk.inverse('\n ' + welcomeMessage + ' \n'));
 
-var useYarn = Boolean(program.useYarn) || /\.yarn-cache/.test(__dirname);
+var useYarn = Boolean(program.useNpm !== true) && hasYarn()
 
 var npmOptions = {
   useYarn: useYarn

lib/has_yarn.js

@@ -0,0 +1,6 @@
+var spawnSync = require('spawn-sync');
+
+module.exports = function hasYarn() {
+  var result = spawnSync('yarn', ['--version'], { silent: true });
+  return result.status === 0;
+}