Update Convex with no payload to be just like convex with payload but without payload

packages/backend/tests/unit/harness.test.ts

@@ -0,0 +1,13 @@
+import { convexTest } from 'convex-test';
+import { describe, expect, test } from 'vitest';
+
+import schema from '../../convex/schema';
+
+const modules = import.meta.glob('../../convex/**/*.*s');
+
+describe('convex-test harness', () => {
+  test('boots and executes against the project schema', async () => {
+    const t = convexTest(schema, modules);
+    expect(await t.run(() => Promise.resolve(42))).toBe(42);
+  });
+});