Add nested tab group test

src/components/tab-group/tab-group.e2e.ts

@@ -120,4 +120,31 @@ describe('<sl-tab group>', () => {
     expect(slTabShow).toHaveReceivedEventTimes(1);
     expect(slTabShow).toHaveReceivedEventDetail({ name: 'advanced' });
   });
+
+  it('should not hide the active panel when selecting a nested tab', async () => {
+    const page = await newE2EPage({
+      html: `
+        <sl-tab-group>
+        <sl-tab slot="nav" panel="a">Tab A</sl-tab>
+        <sl-tab slot="nav" panel="b">Tab B</sl-tab>
+
+        <sl-tab-panel name="a">
+          <sl-tab-group>
+            <sl-tab slot="nav" panel="c">Tab C</sl-tab>
+            <sl-tab slot="nav" panel="d">Tab D</sl-tab>
+            <sl-tab-panel name="c">Panel C</sl-tab-panel>
+            <sl-tab-panel name="d">Panel D</sl-tab-panel>
+          </sl-tab-group>
+        </sl-tab-panel>
+        <sl-tab-panel name="b">Panel B</sl-tab-panel>
+      </sl-tab-group>
+      `
+    });
+    const nestedTabGroup = await page.find('sl-tab-group sl-tab-group');
+    const tab = await page.find(`sl-tab[panel="d"]`);
+
+    await tab.click();
+
+    expect(await nestedTabGroup.isVisible()).toBe(true);
+  });
 });