fix: set aria-describedby when overlay is a false but valid node (#544)

* fix: set aria-describedby when overlay is a falsy but valid node

overlay values like 0 are valid renderable content, but the previous
`overlay && open` check treated them as absent and skipped
aria-describedby even while the tooltip was visible.

* feat: add new tests

Author: zigzagdev

src/Tooltip.tsx

@@ -121,7 +121,7 @@ const Tooltip = React.forwardRef<TooltipRef, TooltipProps>((props, ref) => {
   const getChildren: TriggerProps['children'] = ({ open }) => {
     const child = React.Children.only(children);
     const childAriaDescribedBy = (child.props as React.AriaAttributes)['aria-describedby'];
-    const ariaDescribedBy = [childAriaDescribedBy, overlay && open ? mergedId : undefined]
+    const ariaDescribedBy = [childAriaDescribedBy, overlay != null && open ? mergedId : undefined]
       .filter(Boolean)
       .join(' ');
     const ariaProps: React.AriaAttributes = {

tests/index.test.tsx

@@ -597,6 +597,35 @@ describe('rc-tooltip', () => {
       expect(trigger).toHaveAttribute('aria-describedby', 'existing-description');
     });
 
+    it('should set aria-describedby when overlay is a falsy but valid node like 0', () => {
+      const { container } = render(
+        <Tooltip overlay={0} visible>
+          <button>Click me</button>
+        </Tooltip>,
+      );
+
+      const trigger = container.querySelector('button');
+      const describedBy = trigger.getAttribute('aria-describedby');
+      expect(describedBy).toBeTruthy();
+      expect(document.getElementById(describedBy)).toHaveTextContent('0');
+    });
+
+    it('should not set aria-describedby when overlay is null or undefined', () => {
+      const { container: nullContainer } = render(
+        <Tooltip overlay={null} visible>
+          <button>Click me</button>
+        </Tooltip>,
+      );
+      expect(nullContainer.querySelector('button')).not.toHaveAttribute('aria-describedby');
+
+      const { container: undefinedContainer } = render(
+        <Tooltip overlay={undefined} visible>
+          <button>Click me</button>
+        </Tooltip>,
+      );
+      expect(undefinedContainer.querySelector('button')).not.toHaveAttribute('aria-describedby');
+    });
+
     it('should preserve original props of children', () => {
       const onMouseEnter = jest.fn();