Use yarn add --force to simplify install script

Author: devversion

scripts/install-angular-snapshots.js

@@ -1,42 +1,27 @@
-/*
- * Script that re-installs all Angular dependencies using the GitHub build snapshots. We need to
- * do this after the locked node modules have been installed because otherwise `--frozen-lockfile`
- * would complain about outdated lock files.
+/**
+ * Script that re-installs all Angular dependencies using the GitHub build snapshots.
+ * We need to do this after the locked node modules have been installed because
+ * otherwise "--frozen-lockfile" would complain about outdated lock files.
  */
 
 const path = require('path');
-const fs = require('fs');
 const execSync = require('child_process').execSync;
 const packageJsonPath = path.join(__dirname, '../package.json');
-const packageJson = require(packageJsonPath);
+const {dependencies, devDependencies} = require(packageJsonPath);
 
-/** 
- * Updates all Angular dependencies for a given type by replacing the version with a Github URL
- * that refers to the corresponding Github builds repository.
- * @param dependencyType Either `dependencies` or `devDependencies` 
-*/
-function updateAngularDependencies(dependencyType) {
-  Object.keys(packageJson[dependencyType])
-    .filter(depName => depName.startsWith('@angular/'))
-    .forEach(depName => {
-      packageJson[dependencyType][depName] = `github:angular/${depName.split('/')[1]}-builds`
-    });
-}
+// List of snapshot package URLs that can be passed to Yarn in order to install the Angular
+// snapshot builds from Github (e.g. github:angular/core-builds)
+const snapshotPackageUrls = Object.keys({...dependencies, ...devDependencies})
+  .filter(depName => depName.startsWith('@angular/'))
+  .map(depName => `github:angular/${depName.split('/')[1]}-builds`);
 
-// Update `dependencies` and `devDependencies` in the "packageJson" object, so that
-// we can write the changes to disk afterwards. We cannot just run `yarn add ${all_deps}` because
-// Yarn will complain that some dependencies are already set up in the package.json file.
-updateAngularDependencies('dependencies');
-updateAngularDependencies('devDependencies');
-
-// Write the dependencies changes to the original "package.json" file.
-fs.writeFileSync(packageJsonPath, JSON.stringify(packageJson, null, 2));
-
-// Run "yarn install" in order to install the packages that have been written to the package.json.
-execSync('yarn install', {
+// Run "yarn add" in order to install the packages that have been written to the package.json.
+// Note that we need to pass "--force" because Yarn will complain for packages that are
+// already specified in the "package.json".
+execSync(`yarn add ${snapshotPackageUrls.join(' ')} --force`, {
   stdio: 'inherit',
   shell: true,
   cwd: path.join(__dirname, '../')
 });
 
-console.log('Finished installing the Angular snapshot builds.');
+console.log('Finished installing the Angular snapshot builds.');