fix(react-button): do not expose default menuIcon in useMenuButtonBase_unstable

change/@fluentui-react-button-de57007e-ed5d-4006-b38f-0715f6088ed4.json

@@ -0,0 +1,7 @@
+{
+  "type": "patch",
+  "comment": "fix: do not expose default icon in base hook",
+  "packageName": "@fluentui/react-button",
+  "email": "vgenaev@gmail.com",
+  "dependentChangeType": "patch"
+}

packages/react-components/react-button/library/src/components/MenuButton/useMenuButton.test.tsx

@@ -1,9 +1,11 @@
 import * as React from 'react';
+import { render } from '@testing-library/react';
 import { renderHook } from '@testing-library/react-hooks';
 import '@testing-library/jest-dom';
 import { ButtonContextProvider } from '../../contexts/ButtonContext';
 import type { ButtonContextValue } from '../../contexts/ButtonContext';
 import { useMenuButton_unstable } from './useMenuButton';
+import { MenuButton } from './MenuButton';
 
 const wrap = (contextValue: ButtonContextValue = {}): React.FC<{ children?: React.ReactNode }> => {
   const Wrapper: React.FC<{ children?: React.ReactNode }> = ({ children }) => (
@@ -19,10 +21,9 @@ describe('useMenuButton_unstable', () => {
     expect(result.current.components).toEqual({ root: 'button', icon: 'span', menuIcon: 'span' });
   });
 
-  it('renders a menuIcon slot with a default chevron icon', () => {
-    const { result } = renderHook(() => useMenuButton_unstable({}, React.createRef()));
-    expect(result.current.menuIcon).toBeDefined();
-    expect(React.isValidElement(result.current.menuIcon?.children)).toBe(true);
+  it('renders a menuIcon slot with a default icon', () => {
+    const result = render(<MenuButton />);
+    expect(result.container.querySelector('svg')).toBeInTheDocument();
   });
 
   it('preserves a user-provided menuIcon over the default chevron', () => {
@@ -33,6 +34,16 @@ describe('useMenuButton_unstable', () => {
     expect(result.current.menuIcon?.children).toBe(customIcon);
   });
 
+  it('renders the default chevron when menuIcon is explicitly undefined', () => {
+    const result = render(<MenuButton menuIcon={undefined} />);
+    expect(result.container.querySelector('svg')).toBeInTheDocument();
+  });
+
+  it('hides the menuIcon slot when menuIcon is null', () => {
+    const { result } = renderHook(() => useMenuButton_unstable({ menuIcon: null }, React.createRef()));
+    expect(result.current.menuIcon).toBeUndefined();
+  });
+
   it('defaults aria-expanded to false when not provided', () => {
     const { result } = renderHook(() => useMenuButton_unstable({}, React.createRef()));
     expect(result.current.root['aria-expanded']).toBe(false);

packages/react-components/react-button/library/src/components/MenuButton/useMenuButton.tsx

@@ -10,6 +10,10 @@ import type { MenuButtonBaseProps, MenuButtonBaseState, MenuButtonProps, MenuBut
 /**
  * Base hook for MenuButton.
  *
+ * The `menuIcon` slot ships no icon of its own and only renders when a consumer
+ * provides one, so headless consumers can supply their own visuals. The styled
+ * `useMenuButton_unstable` adds the default chevron on top of this.
+ *
  * @param props - User provided props to the MenuButton component.
  * @param ref - User provided ref to be passed to the MenuButton component.
  */
@@ -40,10 +44,6 @@ export const useMenuButtonBase_unstable = (
     },
 
     menuIcon: slot.optional(menuIcon, {
-      defaultProps: {
-        children: <ChevronDownRegular />,
-      },
-      renderByDefault: true,
       elementType: 'span',
     }),
   };
@@ -61,8 +61,14 @@ export const useMenuButton_unstable = (
   ref: React.Ref<HTMLButtonElement | HTMLAnchorElement>,
 ): MenuButtonState => {
   const { size: contextSize } = useButtonContext();
-  const { appearance = 'secondary', shape = 'rounded', size = contextSize ?? 'medium', ...baseProps } = props;
-  const baseState = useMenuButtonBase_unstable(baseProps, ref);
+  const { appearance = 'secondary', menuIcon, shape = 'rounded', size = contextSize ?? 'medium', ...baseProps } = props;
+  const baseState = useMenuButtonBase_unstable(
+    {
+      ...baseProps,
+      menuIcon: menuIcon === null ? null : { children: <ChevronDownRegular />, ...slot.resolveShorthand(menuIcon) },
+    },
+    ref,
+  );
 
   return {
     ...baseState,

packages/react-components/react-button/library/src/components/MenuButton/useMenuButtonBase.test.tsx

@@ -4,9 +4,18 @@ import '@testing-library/jest-dom';
 import { useMenuButtonBase_unstable } from './useMenuButton';
 
 describe('useMenuButtonBase_unstable', () => {
-  it('returns a menuIcon slot by default', () => {
+  it('does not render the menuIcon slot when none is provided', () => {
     const { result } = renderHook(() => useMenuButtonBase_unstable({}, React.createRef()));
+    expect(result.current.menuIcon).toBeUndefined();
+  });
+
+  it('renders the menuIcon slot only when one is provided, shipping no default icon', () => {
+    const customIcon = <span data-testid="custom-menu-icon" />;
+    const { result } = renderHook(() =>
+      useMenuButtonBase_unstable({ menuIcon: { children: customIcon } }, React.createRef()),
+    );
     expect(result.current.menuIcon).toBeDefined();
+    expect(result.current.menuIcon?.children).toBe(customIcon);
   });
 
   it('forces aria-expanded to a boolean on root', () => {