feat: pre-generate package-lock for faster install (#233)

generators/app/index.js

@@ -10,6 +10,7 @@ const constants = require('./constants');
 const naming = require('./naming');
 const packageJSON = require('./package-json');
 const validators = require('./validators');
+const spawnSync = require('child_process').spawnSync;
 
 module.exports = class extends Generator {
 
@@ -221,7 +222,8 @@ module.exports = class extends Generator {
       'test/_plugin.test.js',
       '_index.html',
       '_CONTRIBUTING.md',
-      '_README.md'
+      '_README.md',
+      '_package-lock.json'
     ];
 
     this._promptsToFilter = [];
@@ -331,7 +333,34 @@ module.exports = class extends Generator {
    * we don't want to run that (or depend on it in any way).
    */
   install() {
-    this.npmInstall();
+    const result = spawnSync('npm', ['--version']);
+
+    // no access to npm uh oh, lets let yeoman throw an error
+    if (result.status !== 0) {
+      return this.npmInstall();
+    }
+
+    // get the major version for npm
+    const major = parseFloat(result.stdout.toString().trim().split('.')[0]);
+
+    if (!major || major <= 5) {
+      return this.npmInstall();
+    }
+
+    // this.npmInstall automaticall handles
+    // skipInstall, but our custom  install does not.
+    // handle it now.
+    if (this.options.skipInstall) {
+      this.log('Skipping Install, to install later please run: npm i --package-lock-only && npm ci');
+      return;
+    }
+
+    // if we are on npm greater than 6
+    // save time by updating package-lock-only
+    // and then running npm ci
+    spawnSync('npm', ['i', '--package-lock-only'], {stdio: 'inherit', cwd: this.destinationRoot()});
+    spawnSync('npm', ['ci'], {stdio: 'inherit', cwd: this.destinationRoot()});
+
   }
 
   /**