add some failing tests to show the problem with pageParam typings

Author: TkDodo

packages/react-query/src/__tests__/useInfiniteQuery.type.test.tsx

@@ -0,0 +1,61 @@
+import { useInfiniteQuery } from '../useInfiniteQuery'
+import { useQuery } from '../useQuery'
+import type { Expect, Equal } from './utils'
+import { doNotExecute } from './utils'
+import { QueryClient } from '@tanstack/query-core'
+
+describe('pageParam', () => {
+  it('defaultPageParam should define type of param passed to queryFunctionContext', () => {
+    doNotExecute(() => {
+      useInfiniteQuery({
+        queryKey: ['key'],
+        queryFn: ({ pageParam }) => {
+          const result: Expect<Equal<number, typeof pageParam>> = true
+          return result
+        },
+        defaultPageParam: 1,
+        getNextPageParam: () => undefined,
+      })
+    })
+  })
+
+  it('there should be no pageParam passed to queryFn of useQuery', () => {
+    doNotExecute(() => {
+      useQuery({
+        queryKey: ['key'],
+        // @ts-expect-error there should be no pageParam passed to queryFn of useQuery
+        queryFn: ({ pageParam }) => {
+          return String(pageParam)
+        },
+      })
+    })
+  })
+
+  it('defaultPageParam should define type of param passed to queryFunctionContext for fetchInfiniteQuery', () => {
+    doNotExecute(() => {
+      const queryClient = new QueryClient()
+      queryClient.fetchInfiniteQuery({
+        queryKey: ['key'],
+        queryFn: ({ pageParam }) => {
+          const result: Expect<Equal<number, typeof pageParam>> = true
+          return result
+        },
+        defaultPageParam: 1,
+      })
+    })
+  })
+
+  it('defaultPageParam should define type of param passed to queryFunctionContext for prefetchInfiniteQuery', () => {
+    doNotExecute(() => {
+      const queryClient = new QueryClient()
+      queryClient.prefetchInfiniteQuery({
+        queryKey: ['key'],
+        queryFn: ({ pageParam }) => {
+          const result: Expect<Equal<number, typeof pageParam>> = true
+          return result
+        },
+        defaultPageParam: 1,
+      })
+    })
+  })
+})

packages/react-query/src/__tests__/useQuery.types.test.tsx

@@ -1,14 +1,6 @@
 import { useQuery } from '../useQuery'
-
-export type Equal<X, Y> = (<T>() => T extends X ? 1 : 2) extends <
-  T,
->() => T extends Y ? 1 : 2
-  ? true
-  : false
-
-export type Expect<T extends true> = T
-
-const doNotExecute = (_func: () => void) => true
+import type { Expect, Equal } from './utils'
+import { doNotExecute } from './utils'
 
 describe('initialData', () => {
   describe('Config object overload', () => {

packages/react-query/src/__tests__/utils.tsx

@@ -79,6 +79,14 @@ export function expectType<T>(_: T): void {
   return undefined
 }
 
+export type Equal<X, Y> = (<T>() => T extends X ? 1 : 2) extends <
+  T,
+>() => T extends Y ? 1 : 2
+  ? true
+  : false
+
+export type Expect<T extends true> = T
+
 /**
  * Assert the parameter is not typed as `any`
  */
@@ -100,3 +108,5 @@ export function setIsServer(isServer: boolean) {
     })
   }
 }
+
+export const doNotExecute = (_func: () => void) => true