test: add a test to ensure the correctness of timezone upgrades

Currently, there's no way to know if a timezone upgrade PR is correct
without building and testing the change locally. This change provides a
solution for that.

Tested in #4.

Signed-off-by: Darshan Sen <[email protected]>

Author: RaisinTen

.github/workflows/timezone-update.yml

@@ -36,6 +36,9 @@ jobs:
 
       - run: ./tools/update-timezone.mjs
 
+      - name: Update the expected timezone version in test
+        run: echo "${{ env.new_version }}" > test/fixtures/tz-version.txt
+
       - name: Open Pull Request
         uses: gr2m/create-or-update-pull-request-action@dc1726cbf4dd3ce766af4ec29cfb660e0125e8ee  # Create a PR or update the Action's existing PR
         env:

test/fixtures/tz-version.txt

@@ -0,0 +1 @@
+2022e

test/parallel/test-tz-version.js

@@ -0,0 +1,12 @@
+'use strict';
+
+require('../common');
+const { path } = require('../common/fixtures');
+
+// This test ensures the correctness of the automated timezone upgrade PRs.
+
+const { strictEqual } = require('assert');
+const { readFileSync } = require('fs');
+
+const expectedVersion = readFileSync(path('tz-version.txt'), 'utf8').trim();
+strictEqual(process.versions.tz, expectedVersion);