fix: no hydration when new promise comes in

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

@@ -1066,4 +1066,82 @@ describe('dehydration and rehydration', () => {
     clientQueryClient.clear()
     serverQueryClient.clear()
   })
+
+  test.only('should overwrite data when a new promise is streamed in', async () => {
+    const serializeDataMock = vi.fn((data: any) => data)
+    const countRef = { current: 0 }
+    // --- server ---
+    const serverQueryClient = createQueryClient({
+      defaultOptions: {
+        dehydrate: {
+          shouldDehydrateQuery: () => true,
+          serializeData: serializeDataMock,
+        },
+      },
+    })
+
+    const query = {
+      queryKey: ['data'],
+      queryFn: async () => {
+        await sleep(10)
+        console.log('queryFn', countRef.current)
+        return countRef.current
+      },
+    }
+
+    const promise = serverQueryClient.prefetchQuery(query)
+
+    const dehydrated = dehydrate(serverQueryClient)
+
+    // --- client ---
+    const deserializeDataMock = vi.fn((data: any) => data)
+    const clientQueryClient = createQueryClient({
+      defaultOptions: {
+        hydrate: {
+          deserializeData: deserializeDataMock,
+        },
+      },
+    })
+
+    hydrate(clientQueryClient, dehydrated)
+
+    await promise
+    await waitFor(() =>
+      expect(clientQueryClient.getQueryData(query.queryKey)).toBe(0),
+    )
+
+    console.log('serialize mock', serializeDataMock.mock.calls)
+
+    expect(serializeDataMock).toHaveBeenCalledTimes(1)
+    expect(serializeDataMock).toHaveBeenCalledWith(0)
+
+    expect(deserializeDataMock).toHaveBeenCalledTimes(1)
+    expect(deserializeDataMock).toHaveBeenCalledWith(0)
+
+    // --- server ---
+    countRef.current++
+    const promise2 = serverQueryClient.prefetchQuery(query)
+
+    const dehydrated2 = dehydrate(serverQueryClient)
+
+    // --- client ---
+
+    hydrate(clientQueryClient, dehydrated2)
+
+    await promise2
+    // await waitFor(() =>
+    //   expect(clientQueryClient.getQueryData(query.queryKey)).toBe(1),
+    // )
+
+    console.log('serialize mock', serializeDataMock.mock.calls)
+
+    expect(serializeDataMock).toHaveBeenCalledTimes(2)
+    expect(serializeDataMock).toHaveBeenCalledWith(1)
+
+    expect(deserializeDataMock).toHaveBeenCalledTimes(2)
+    expect(deserializeDataMock).toHaveBeenCalledWith(1)
+
+    clientQueryClient.clear()
+    serverQueryClient.clear()
+  })
 })

packages/query-core/src/hydration.ts

@@ -177,6 +177,9 @@ export function hydrate(
     const data =
       state.data === undefined ? state.data : deserializeData(state.data)
 
+    console.log('data', data)
+    console.log('query', query)
+
     // Do not hydrate if an existing query exists with newer data
     if (query) {
       if (query.state.dataUpdatedAt < state.dataUpdatedAt) {