feat(HTL-111103): Update unit test

packages/core/src/Drawer/Drawer.spec.tsx

@@ -1,6 +1,8 @@
 import React from 'react'
 import { render } from '../__test__/testing-library'
 import { Drawer } from './Drawer'
+import { Flex } from '../Flex/Flex'
+import { Button } from '../Button/Button'
 
 describe('Drawer', () => {
   test('renders Drawer with no heading', () => {
@@ -48,4 +50,25 @@ describe('Drawer', () => {
     )
     expect(getByText('Custom Heading')).toBeTruthy()
   })
+
+  test('renders Drawer with full custom headers (text, buttons, etc.)', () => {
+    const CustomHeader = (
+      <Flex data-testid='custom-header'>
+        CustomHeader<Button ml='auto'>Click</Button>
+      </Flex>
+    )
+
+    const { getByTestId } = render(
+      <Drawer
+        isOpen={true}
+        placement='right'
+        onClose={jest.fn}
+        onCollapse={jest.fn}
+        customHeader={CustomHeader}
+      >
+        Content
+      </Drawer>
+    )
+    expect(getByTestId('custom-header')).toBeTruthy()
+  })
 })