test(supaworker): add e2e test for worker spawning with message queue

Adds an end-to-end test for verifying worker spawning behavior when processing a large batch
of messages, ensuring proper sequence incrementation and worker scaling

pkgs/supaworker/tests/e2e/worker_spawns_next_worker.test.ts

@@ -0,0 +1,42 @@
+import { sql } from '../sql.ts';
+import { assertGreaterOrEqual } from 'jsr:@std/assert';
+import { delay } from 'jsr:@std/async';
+
+async function seqLastValue(): Promise<number> {
+  const seqResult = await sql`SELECT last_value::integer FROM test_seq`;
+  return seqResult[0].last_value;
+}
+
+Deno.test('should spawn next worker when CPU clock limit hits', async () => {
+  await sql`ALTER SEQUENCE test_seq RESTART WITH 1`;
+  await sql`DELETE FROM supaworker.workers`;
+  await sql`SELECT supaworker.spawn('increment-sequence')`;
+
+  const MESSAGES_TO_SEND = 5000;
+
+  try {
+    await sql`
+      SELECT pgmq.send_batch(
+        'pgflow',
+        ARRAY(
+          SELECT '{}'::jsonb
+          FROM generate_series(1, ${MESSAGES_TO_SEND})
+        )
+      )`;
+
+    let lastVal = 0;
+    while (lastVal < MESSAGES_TO_SEND) {
+      console.log('Polling... current value:', lastVal);
+      await delay(1000);
+      lastVal = await seqLastValue();
+    }
+
+    assertGreaterOrEqual(
+      lastVal,
+      MESSAGES_TO_SEND,
+      'Sequence value should be greater than or equal to the number of messages sent'
+    );
+  } finally {
+    await sql.end();
+  }
+});