add select sl-change test

src/components/select/select.test.ts

@@ -0,0 +1,24 @@
+import { expect, fixture, html, waitUntil } from '@open-wc/testing';
+import sinon from 'sinon';
+
+import '../../../dist/shoelace.js';
+import type SlSelect from './select';
+
+describe('<sl-select>', () => {
+  it('should emit sl-change when the value changes', async () => {
+    const el = (await fixture(html`
+      <sl-select>
+        <sl-menu-item value="option-1">Option 1</sl-menu-item>
+        <sl-menu-item value="option-2">Option 2</sl-menu-item>
+        <sl-menu-item value="option-3">Option 3</sl-menu-item>
+      </sl-select>
+    `)) as SlSelect;
+    const changeHandler = sinon.spy();
+
+    el.addEventListener('sl-change', changeHandler);
+    el.value = 'option-2';
+    await waitUntil(() => changeHandler.calledOnce);
+
+    expect(changeHandler).to.have.been.calledOnce;
+  });
+});