Add script for validating PR title (#4050)

.github/scripts/validate-pr-title.ts

@@ -0,0 +1,68 @@
+#!/usr/bin/env node
+
+// This script validates that a PR title also contains its labels
+// in the title. This is a requirement, because this makes it easier
+// to parse commit messages. For example, for generating a changelog
+// for a particular platform.
+// Usage:
+// PR_TITLE="Make some changes to Android" PR_LABELS="android" node validate-pr-title.ts
+
+export function validateTitle({
+  title,
+  labels
+}: {
+  title: string,
+  labels: Set<string>
+}): { ok: true } | { ok: false, mismatches: string[] } {
+  // these labels are the ones we care about
+  const keywords = new Set(['node', 'core', 'ios', 'android', 'qt']);
+
+  // when labels includes core, only 'core' is required
+  const requiredKeyWords = labels.has('core')
+    ? new Set(['core'])
+    : labels.intersection(keywords);
+
+  title = title.toLocaleLowerCase();
+
+  const actualKeywords = new Set();
+  for (const keyword of requiredKeyWords) {
+    if (title.includes(keyword)) actualKeywords.add(keyword);
+  }
+
+  const mismatches = requiredKeyWords.difference(actualKeywords);
+
+  if (mismatches.size === 0) return { ok: true };
+  return { ok: false, mismatches: [...mismatches] };
+}
+
+if (import.meta.main) {
+  if (!process.env.PR_TITLE) {
+    console.log('::error::PR_TITLE environment variable is not set');
+    process.exit(1);
+  }
+
+  if (!process.env.PR_LABELS) {
+    console.log('::error::PR_LABELS environment variable is not set');
+    process.exit(1);
+  }
+
+  const title = process.env.PR_TITLE;
+  const labelsString = process.env.PR_LABELS.toLowerCase();
+  const labels = new Set(labelsString.split(',').map(l => l.trim()).filter(l => l));
+
+  const result = validateTitle({
+    title,
+    labels
+  });
+  if (result.ok) {
+    console.log('✅ PR labels match the title');
+    process.exit(0);
+  }
+
+  if (!result.ok) {
+    if (result.mismatches.length > 0) {
+      console.log(`::error::PR title does not match PR labels. Mismatched: ${result.mismatches.join(', ')}. Title: "${process.env.PR_TITLE}". Labels: "${process.env.PR_LABELS}"`);
+      process.exit(1);
+    }
+  }
+}