fix: allow using slotted elements in Select

src/Select.tsx

@@ -2,6 +2,7 @@ import {
   type ComponentType,
   type ForwardedRef,
   forwardRef,
+  isValidElement,
   type ReactElement,
   type ReactNode,
   useEffect,
@@ -16,15 +17,35 @@ export * from './generated/Select.js';
 
 export type SelectReactRendererProps = ReactSimpleRendererProps<SelectElement>;
 
+type SelectRenderer = ComponentType<SelectReactRendererProps>;
+
 export type SelectProps = Partial<Omit<_SelectProps, 'children' | 'renderer'>> &
   Readonly<{
-    children?: ReactNode | ComponentType<SelectReactRendererProps>;
-    renderer?: ComponentType<SelectReactRendererProps> | null;
+    children?: ReactNode | SelectRenderer | Array<ReactNode | SelectRenderer>;
+    renderer?: SelectRenderer | null;
   }>;
 
 function Select(props: SelectProps, ref: ForwardedRef<SelectElement>): ReactElement | null {
+  // React.Children.toArray() doesn't allow functions, so we convert manually.
+  const children = Array.isArray(props.children) ? props.children : [props.children];
+
+  // Components with slot attribute should stay in light DOM.
+  const slottedChildren = children.filter((child): child is ReactNode => {
+    return isValidElement(child) && child.props.slot;
+  });
+
+  // Component without slot attribute should go to the overlay.
+  const overlayChildren = children.filter((child): child is ReactNode => {
+    return isValidElement(child) && !slottedChildren.includes(child);
+  });
+
+  const renderFn = children.find((child) => typeof child === 'function');
+
   const innerRef = useRef<SelectElement>(null);
-  const [portals, renderer] = useSimpleOrChildrenRenderer(props.renderer, props.children);
+  const [portals, renderer] = useSimpleOrChildrenRenderer(
+    props.renderer,
+    renderFn || (overlayChildren.length ? overlayChildren : undefined),
+  );
   const finalRef = useMergedRefs(innerRef, ref);
 
   useEffect(() => {
@@ -35,6 +56,7 @@ function Select(props: SelectProps, ref: ForwardedRef<SelectElement>): ReactElem
 
   return (
     <_Select {...props} ref={finalRef} renderer={renderer}>
+      {slottedChildren}
       {portals}
     </_Select>
   );

test/Select.spec.tsx

@@ -96,4 +96,51 @@ describe('Select', () => {
       await expect(findByQuerySelector('vaadin-select-value-button')).to.eventually.have.text('Bar');
     });
   });
+
+  describe('slot', () => {
+    it('should render the element with slot if renderer prop is set', async () => {
+      render(
+        <Select renderer={Renderer}>
+          <div slot="prefix">Value:</div>
+        </Select>,
+      );
+
+      await expect(findByQuerySelector('div[slot="prefix"]')).to.eventually.have.text('Value:');
+    });
+
+    it('should render the element with slot if items prop is set', async () => {
+      render(
+        <Select items={items}>
+          <div slot="prefix">Value:</div>
+        </Select>,
+      );
+
+      await expect(findByQuerySelector('div[slot="prefix"]')).to.eventually.have.text('Value:');
+    });
+
+    it('should render the element with slot if children render function is set', async () => {
+      render(
+        <Select>
+          {Renderer}
+          <div slot="prefix">Value:</div>
+        </Select>,
+      );
+
+      await expect(findByQuerySelector('div[slot="prefix"]')).to.eventually.have.text('Value:');
+    });
+
+    it('should render the element with slot if children component is set', async () => {
+      render(
+        <Select>
+          <ListBox>
+            <Item value="foo">Foo</Item>
+            <Item value="bar">Bar</Item>
+          </ListBox>
+          <div slot="prefix">Value:</div>
+        </Select>,
+      );
+
+      await expect(findByQuerySelector('div[slot="prefix"]')).to.eventually.have.text('Value:');
+    });
+  });
 });

test/kitchen-sink/Row8.tsx

@@ -5,6 +5,7 @@ import { RadioButton } from '../../src/RadioButton.js';
 import { RadioGroup } from '../../src/RadioGroup.js';
 import { RichTextEditor } from '../../src/RichTextEditor.js';
 import { Select } from '../../src/Select.js';
+import { Tooltip } from '../../src/Tooltip.js';
 
 function SelectListBox() {
   return (
@@ -27,7 +28,11 @@ export default function Row8() {
         </RadioButton>
       </RadioGroup>
       <RichTextEditor></RichTextEditor>
-      <Select label="Select" value="2" renderer={SelectListBox} />
+      <Select label="Select" value="2">
+        {SelectListBox}
+        <span slot="prefix">+</span>
+        <Tooltip slot="tooltip" text="Select tooltip"></Tooltip>
+      </Select>
     </BoardRow>
   );
 }