Config: Add support for a config file (#9)

- Adds the ability to store audit arguments in a configuration file named css-audit.config.js in the root of the project, fixes #8
- Supports multiple property-values audits from the config

Co-authored-by: Kelly Dwan <ryelle@users.noreply.github.com>

.nvmrc

@@ -0,0 +1 @@
+14

README.md

@@ -8,14 +8,14 @@ To run this yourself, download or clone this repo, then install the dependencies
 $ git clone git@github.com:ryelle/css-audit.git
 $ cd css-audit
 $ npm install
-$ npm run css-audit
+$ npm run css-audit -- <files...>
 ```
 
 If you want to work on the audits yourself, [fork this repo](https://help.github.com/en/github/getting-started-with-github/fork-a-repo) to your account first. You can submit issues or PRs.
 
 ## Running Audits
 
-To run the audits, you need a list of CSS files, and to indicate which audits you want to run. `yarn` and `npm` both automatically expand globs (`folder/*`), so you can use that, or pass in a list of CSS files. The audits are described below.
+To run the audits, you need a list of CSS files, and to indicate which audits you want to run. `yarn` and `npm` both automatically expand globs (`folder/*`), so you can use that, or pass in a list of CSS files. The audits are described below, and can be run via the following CLI args, or via configuration file (described in the next section).
 
 ```
 $ npm run css-audit -- <files ...> [options]
@@ -35,6 +35,26 @@ Usage: css-audit -- <files...> [options]
 --help            Show this message.
 ```
 
+
+### Configuration File
+
+The program will prioritize configuration from CLI arguments, and will fallback to configuration stored in a file called `css-audit.config.js`.
+
+```
+module.exports = {
+	format: 'json',
+	audits: [
+		'colors',
+		'important',
+		'display-none',
+		'selectors',
+		'media-queries',
+		[ 'property-values', 'font-size' ],
+		[ 'property-values', 'padding-top,padding-bottom' ],
+	],
+};
+```
+
 ## Generating HTML Reports
 
 To generate an HTML report, use the `--format=html` option and specify a name for the file with the `--filename=name` option. This will output a `{name}.html` file in public/ that is viewable on Github Pages.
@@ -45,6 +65,8 @@ For example, generating a report for wp-admin using the below strategy for pulli
 npm run css-audit -- v5.5/**/* --format=html --all --filename=wp-admin
 ```
 
+In the configuration file, the argument `filename` can be added as a simple property: value combination, the same as `format` in the example.
+
 ## Getting core CSS files
 
 You can download the source files of CSS (not minified or RTL'd) from the svn repository. The following code will create a new directory, `v5.5`, and download just the files from each `css` folder.

css-audit.config.js

@@ -0,0 +1,6 @@
+module.exports = {
+	format: 'html',
+	all: true,
+	filename: 'wp-admin',
+	audits: [ [ 'property-values', 'font-size' ] ],
+};

index.js

@@ -0,0 +1,38 @@
+/**
+ * Node dependencies
+ */
+const fs = require( 'fs' );
+const path = require( 'path' );
+
+/**
+ * Internal dependencies
+ */
+const { runAudits } = require( './src/run' );
+const { getArg, getFileArgsFromCLI, getHelp } = require( './src/utils/cli' );
+
+const input = getFileArgsFromCLI();
+
+if ( getArg( '--help', true ) || ! input.length ) {
+	console.log( getHelp() );
+	process.exit( 0 );
+}
+
+const cssFiles = [];
+input.forEach( ( file ) => {
+	const filePath = path.resolve( process.env.INIT_CWD, file );
+	const stats = fs.statSync( filePath );
+	if ( stats.isDirectory() ) {
+		return;
+	}
+	if ( file.match( /min\.css$/ ) ) {
+		return;
+	}
+	cssFiles.push( {
+		name: file,
+		content: String( fs.readFileSync( filePath ) ),
+	} );
+} );
+
+const result = runAudits( cssFiles );
+
+console.log( result );