fix: correct type inference for props when initialProps is used

src/__tests__/renderHook.test.tsx

@@ -60,3 +60,37 @@ test('allows wrapper components', async () => {
 
  expect(result.current).toEqual('provided');
 });
+
+const useMyHook = (param: number | undefined) => {
+ return param;
+};
+
+test('props type is infered correctly when initial props is defined', () => {
+ const { result, rerender } = renderHook(
+ (num: number | undefined) => useMyHook(num),
+ {
+ initialProps: 5,
+ }
+ );
+
+ expect(result.current).toBe(5);
+
+ rerender(6);
+
+ expect(result.current).toBe(6);
+});
+
+test('props type is infered correctly when initial props is explicitly undefined', () => {
+ const { result, rerender } = renderHook(
+ (num: number | undefined) => useMyHook(num),
+ {
+ initialProps: undefined,
+ }
+ );
+
+ expect(result.current).toBeUndefined();
+
+ rerender(6);
+
+ expect(result.current).toBe(6);
+});

src/renderHook.tsx

@@ -8,16 +8,12 @@ export type RenderHookResult<Result, Props> = {
  unmount: () => void;
 };
 
-export type RenderHookOptions<Props> = Props extends
- | object
- | string
- | number
- | boolean
- ? {
- initialProps: Props;
+export type RenderHookOptions<Props> =
+ | {
+ initialProps?: Props;
  wrapper?: ComponentType<any>;
  }
- : { wrapper?: ComponentType<any>; initialProps?: never } | undefined;
+ | undefined;
 
 export function renderHook<Result, Props>(
  renderCallback: (props: Props) => Result,