test(query-core): add test case for infiniteQueryBehavior (#9101)

Co-authored-by: Jonghyeon Ko <[email protected]>

Author: minseong0324

packages/query-core/src/__tests__/infiniteQueryBehavior.test.tsx

@@ -441,4 +441,63 @@ describe('InfiniteQueryBehavior', () => {
 
     unsubscribe()
   })
+
+  test('InfiniteQueryBehavior should not fetch next page when getNextPageParam returns null', async () => {
+    const key = queryKey()
+
+    const observer = new InfiniteQueryObserver(queryClient, {
+      queryKey: key,
+      queryFn: ({ pageParam }) => sleep(0).then(() => pageParam),
+      getNextPageParam: (lastPage) => (lastPage === 1 ? null : lastPage + 1),
+      initialPageParam: 1,
+    })
+
+    let observerResult:
+      | InfiniteQueryObserverResult<InfiniteData<number, unknown>, Error>
+      | undefined
+
+    const unsubscribe = observer.subscribe((result) => {
+      observerResult = result
+    })
+
+    await vi.waitFor(() =>
+      expect(observerResult).toMatchObject({
+        isFetching: false,
+        data: { pages: [1], pageParams: [1] },
+      }),
+    )
+
+    await observer.fetchNextPage()
+
+    expect(observerResult).toMatchObject({
+      isFetching: false,
+      data: { pages: [1], pageParams: [1] },
+    })
+
+    unsubscribe()
+  })
+
+  test('InfiniteQueryBehavior should use persister when provided', async () => {
+    const key = queryKey()
+
+    const persisterSpy = vi.fn().mockImplementation(async (fn) => {
+      return await fn()
+    })
+
+    const observer = new InfiniteQueryObserver(queryClient, {
+      queryKey: key,
+      queryFn: ({ pageParam }) => sleep(0).then(() => pageParam),
+      getNextPageParam: (lastPage) => lastPage + 1,
+      initialPageParam: 1,
+      persister: persisterSpy,
+    })
+
+    const unsubscribe = observer.subscribe(() => {})
+
+    await vi.waitFor(() => {
+      expect(persisterSpy).toHaveBeenCalledTimes(1)
+    })
+
+    unsubscribe()
+  })
 })