Build/Test Tools: Introduce Install-changed. It keeps a hash of `pack…

…age.json` and compares it when run. If it has any changes, it runs `npm install`.

This keeps `node_modules` always updated and is useful not only when the packages have been updated, but also when the working copy has been "reverted" to an earlier revision.

Fixes #49594.

git-svn-id: https://develop.svn.wordpress.org/trunk@47497 602fd350-edb4-49c9-b593-d223f7449a82

.gitignore

@@ -28,6 +28,7 @@ wp-tests-config.php
 /src/wp-includes/css/dist
 /src/wp-includes/css/*.min.css
 /src/wp-includes/css/*-rtl.css
+/packagehash.txt
 
 # Files and folders that get created in wp-content
 /src/wp-content/blogs.dir

Gruntfile.js

@@ -2,6 +2,7 @@
 /* jshint esversion: 6 */
 /* globals Set */
 var webpackConfig = require( './webpack.config' );
+var installChanged = require( 'install-changed' );
 
 module.exports = function(grunt) {
 	var path = require('path'),
@@ -41,6 +42,9 @@ module.exports = function(grunt) {
 		);
 	}
 
+	// First do `npm install` if package.json has changed.
+	installChanged.watchPackage();
+
 	// Load tasks.
 	require('matchdep').filterDev(['grunt-*', '!grunt-legacy-util']).forEach( grunt.loadNpmTasks );
 	// Load legacy utils.

package.json

@@ -59,6 +59,7 @@
 		"grunt-sass": "~3.1.0",
 		"grunt-webpack": "^3.1.3",
 		"ink-docstrap": "1.3.2",
+		"install-changed": "1.1.0",
 		"jquery-migrate": "1.4.1",
 		"matchdep": "~2.0.0",
 		"node-sass": "~4.13.1",