test(@toss/utils): Add new test for loadScript (#432)

packages/common/utils/src/loadScript.spec.ts

@@ -0,0 +1,26 @@
+import * as deviceModule from './device/isServer';
+import { loadScript } from './loadScript';
+
+describe('loadScript', () => {
+  it('should immediately resolve with a Promise in a server environment', async () => {
+    jest.spyOn(deviceModule, 'isServer').mockReturnValue(true);
+    await expect(loadScript('test-script.js')).resolves.toBeUndefined();
+  });
+
+  it('should immediately resolve with a Promise if the script is already loaded or loading', async () => {
+    jest.spyOn(deviceModule, 'isServer').mockReturnValue(false);
+    const script = document.createElement('script');
+    script.src = 'test-script.js';
+    document.body.appendChild(script);
+    await expect(loadScript('test-script.js')).resolves.toBeUndefined();
+  });
+
+  it('should append a script element to the document body and resolve the Promise on load event', () => {
+    jest.spyOn(deviceModule, 'isServer').mockReturnValue(false);
+    const source = 'https://example.com/script.js';
+    loadScript(source);
+
+    const scriptElement = document.querySelector(`script[src="${source}"]`);
+    expect(scriptElement).toBeTruthy();
+  });
+});