test: add unit test

packages/subapp-server/test/spec/utils.spec.js

@@ -1,3 +1,20 @@
 "use strict";
 
-describe("subapp-server utils", () => {});
+const chai = require('chai');
+const expect = chai.expect;
+const { until } = require("../../lib/utils");
+
+describe('subapp-server utils', function() {
+  this.timeout(8000);
+
+  it('should resolve when the condition is met before the max wait time', async function() {
+    let conditionMet = false;
+    setTimeout(() => {
+      conditionMet = true;
+    }, 1000); 
+
+    await until(() => conditionMet, 3000);
+    expect(conditionMet).to.be.true;
+  });
+
+});