build: create script to update integration lock files (angular#49787)

* Adds a small script to conveniently re-generate lock files for
  integration tests.
* Updates the `.gitignore` for integration tests to ignore node
  modules. Some tests do not have a `.gitignore` (like the CLI
  boilerplate tests).

PR Close angular#49787

Author: devversion

integration/.gitignore

@@ -6,4 +6,8 @@ tmp/
 */src/*.js
 !karma.conf.js
 **/.yarn_local_cache*
-**/NPM_PACKAGE_MANIFEST.json
+**/NPM_PACKAGE_MANIFEST.json
+
+*/node_modules/
+
+.tmp-yarn-cache/

integration/update-lock-files.mjs

@@ -0,0 +1,32 @@
+#!/usr/bin/env node
+
+/**
+ * Script that deletes all `yarn.lock` files for integration tests and
+ * re-builds them from scratch. This script is useful as lock fils in
+ * integration tests are not necessarily up-to-date, given dependencies
+ * being linked from the root `/package.json`, or locally-built 1st party
+ * packages being used from tarball archives.
+ */
+
+import childProcess from 'child_process';
+import url from 'url';
+import path from 'path';
+import glob from 'glob';
+import fs from 'fs';
+
+const containingDir = path.dirname(url.fileURLToPath(import.meta.url));
+const testDirs = glob.sync('*/BUILD.bazel', {cwd: containingDir})
+                     .map((d) => path.join(containingDir, path.dirname(d)));
+
+const yarnTestTmpDir = path.join(containingDir, '.tmp-yarn-cache');
+
+for (const testDir of testDirs) {
+  fs.rmSync(path.join(testDir, 'yarn.lock'));
+  childProcess.spawnSync('yarn', ['install', '--cache-folder', yarnTestTmpDir], {
+    cwd: testDir,
+    shell: true,
+    stdio: 'inherit',
+  });
+}
+
+fs.rmSync(yarnTestTmpDir, {recursive: true});