Fix additional re-render when calling fetchMore from useSuspenseQuery when using startTransition.

.changeset/rich-hotels-sniff.md

@@ -0,0 +1,5 @@
+---
+"@apollo/client": patch
+---
+
+Fix issue where calling `fetchMore` from a suspense-enabled hook inside `startTransition` caused an unnecessary rerender.

.size-limits.json

@@ -1,4 +1,4 @@
 {
-  "dist/apollo-client.min.cjs": 39209,
+  "dist/apollo-client.min.cjs": 39211,
   "import { ApolloClient, InMemoryCache, HttpLink } from \"dist/index.js\" (production)": 32584
 }

src/react/hooks/__tests__/useBackgroundQuery.test.tsx

@@ -4927,25 +4927,6 @@ describe("fetchMore", () => {
       expect(renderedComponents).toStrictEqual([App, SuspenseFallback]);
     }
 
-    // TODO: Determine why we have this extra render here.
-    // Possibly related: https://github.com/apollographql/apollo-client/issues/11315
-    {
-      const { snapshot } = await Profiler.takeRender();
-
-      expect(snapshot.result).toEqual({
-        data: {
-          letters: [
-            { __typename: "Letter", position: 1, letter: "A" },
-            { __typename: "Letter", position: 2, letter: "B" },
-            { __typename: "Letter", position: 3, letter: "C" },
-            { __typename: "Letter", position: 4, letter: "D" },
-          ],
-        },
-        error: undefined,
-        networkStatus: NetworkStatus.ready,
-      });
-    }
-
     {
       const { snapshot } = await Profiler.takeRender();
 
@@ -5034,25 +5015,6 @@ describe("fetchMore", () => {
       expect(renderedComponents).toStrictEqual([App, SuspenseFallback]);
     }
 
-    // TODO: Determine why we have this extra render here.
-    // Possibly related: https://github.com/apollographql/apollo-client/issues/11315
-    {
-      const { snapshot } = await Profiler.takeRender();
-
-      expect(snapshot.result).toEqual({
-        data: {
-          letters: [
-            { __typename: "Letter", position: 1, letter: "A" },
-            { __typename: "Letter", position: 2, letter: "B" },
-            { __typename: "Letter", position: 3, letter: "C" },
-            { __typename: "Letter", position: 4, letter: "D" },
-          ],
-        },
-        error: undefined,
-        networkStatus: NetworkStatus.ready,
-      });
-    }
-
     {
       const { snapshot } = await Profiler.takeRender();
 
@@ -5245,39 +5207,6 @@ describe("fetchMore", () => {
       });
     }
 
-    // TODO: Determine why we have this extra render here. This should mimic
-    // the update in the next render where we see <App /> included in the
-    // rerendered components.
-    // Possibly related: https://github.com/apollographql/apollo-client/issues/11315
-    {
-      const { snapshot, renderedComponents } = await Profiler.takeRender();
-
-      expect(renderedComponents).toStrictEqual([ReadQueryHook]);
-      expect(snapshot).toEqual({
-        isPending: false,
-        result: {
-          data: {
-            todos: [
-              {
-                __typename: "Todo",
-                id: "1",
-                name: "Clean room",
-                completed: false,
-              },
-              {
-                __typename: "Todo",
-                id: "2",
-                name: "Take out trash",
-                completed: true,
-              },
-            ],
-          },
-          error: undefined,
-          networkStatus: NetworkStatus.ready,
-        },
-      });
-    }
-
     {
       // Eventually we should see the updated todos content once its done
       // suspending.

src/react/hooks/__tests__/useSuspenseQuery.test.tsx

@@ -1,4 +1,4 @@
-import React, { Fragment, StrictMode, Suspense } from "react";
+import React, { Fragment, StrictMode, Suspense, useTransition } from "react";
 import {
   act,
   screen,
@@ -51,7 +51,15 @@ import {
   RefetchWritePolicy,
   WatchQueryFetchPolicy,
 } from "../../../core/watchQueryOptions";
-import { profile, spyOnConsole } from "../../../testing/internal";
+import {
+  PaginatedCaseData,
+  PaginatedCaseVariables,
+  createProfiler,
+  profile,
+  setupPaginatedCase,
+  spyOnConsole,
+  useTrackRenders,
+} from "../../../testing/internal";
 
 type RenderSuspenseHookOptions<Props, TSerializedCache = {}> = Omit<
   RenderHookOptions<Props>,
@@ -9978,6 +9986,129 @@ describe("useSuspenseQuery", () => {
     });
   });
 
+  // https://github.com/apollographql/apollo-client/issues/11315
+  it("fetchMore does not cause extra render", async () => {
+    const { query, link } = setupPaginatedCase();
+
+    const user = userEvent.setup();
+    const client = new ApolloClient({
+      cache: new InMemoryCache({
+        typePolicies: {
+          Query: {
+            fields: {
+              letters: offsetLimitPagination(),
+            },
+          },
+        },
+      }),
+      link,
+    });
+
+    const Profiler = createProfiler({
+      initialSnapshot: {
+        result: null as UseSuspenseQueryResult<
+          PaginatedCaseData,
+          PaginatedCaseVariables
+        > | null,
+      },
+    });
+
+    function SuspenseFallback() {
+      useTrackRenders();
+
+      return <div>Loading...</div>;
+    }
+
+    function App() {
+      useTrackRenders();
+      const [isPending, startTransition] = useTransition();
+      const result = useSuspenseQuery(query, {
+        variables: { offset: 0, limit: 2 },
+      });
+      const { data, fetchMore } = result;
+
+      Profiler.mergeSnapshot({ result });
+
+      return (
+        <button
+          disabled={isPending}
+          onClick={() =>
+            startTransition(() => {
+              fetchMore({
+                variables: {
+                  offset: data.letters.length,
+                  limit: data.letters.length + 1,
+                },
+              });
+            })
+          }
+        >
+          Fetch next
+        </button>
+      );
+    }
+
+    render(<App />, {
+      wrapper: ({ children }) => (
+        <ApolloProvider client={client}>
+          <Profiler>
+            <Suspense fallback={<SuspenseFallback />}>{children}</Suspense>
+          </Profiler>
+        </ApolloProvider>
+      ),
+    });
+
+    {
+      const { renderedComponents } = await Profiler.takeRender();
+
+      expect(renderedComponents).toStrictEqual([SuspenseFallback]);
+    }
+
+    {
+      const { snapshot, renderedComponents } = await Profiler.takeRender();
+
+      expect(renderedComponents).toStrictEqual([App]);
+      expect(snapshot.result?.data).toEqual({
+        letters: [
+          { __typename: "Letter", letter: "A", position: 1 },
+          { __typename: "Letter", letter: "B", position: 2 },
+        ],
+      });
+    }
+
+    await act(() => user.click(screen.getByText("Fetch next")));
+
+    {
+      const { snapshot, renderedComponents } = await Profiler.takeRender();
+
+      expect(renderedComponents).toStrictEqual([App]);
+      expect(screen.getByText("Fetch next")).toBeDisabled();
+      expect(snapshot.result?.data).toEqual({
+        letters: [
+          { __typename: "Letter", letter: "A", position: 1 },
+          { __typename: "Letter", letter: "B", position: 2 },
+        ],
+      });
+    }
+
+    {
+      const { snapshot, renderedComponents } = await Profiler.takeRender();
+
+      expect(renderedComponents).toStrictEqual([App]);
+      expect(snapshot.result?.data).toEqual({
+        letters: [
+          { __typename: "Letter", letter: "A", position: 1 },
+          { __typename: "Letter", letter: "B", position: 2 },
+          { __typename: "Letter", letter: "C", position: 3 },
+          { __typename: "Letter", letter: "D", position: 4 },
+          { __typename: "Letter", letter: "E", position: 5 },
+        ],
+      });
+    }
+
+    await expect(Profiler).not.toRerender();
+  });
+
   describe.skip("type tests", () => {
     it("returns unknown when TData cannot be inferred", () => {
       const query = gql`

src/react/internal/cache/QueryReference.ts

@@ -379,10 +379,22 @@ export class InternalQueryReference<TData = unknown> {
     // promise is resolved correctly.
     returnedPromise
       .then((result) => {
-        if (this.promise.status === "pending") {
-          this.result = result;
-          this.resolve?.(result);
-        }
+        // In the case of `fetchMore`, this promise is resolved before a cache
+        // result is emitted due to the fact that `fetchMore` sets a `no-cache`
+        // fetch policy and runs `cache.batch` in its `.then` handler. Because
+        // the timing is different, we accidentally run this update twice
+        // causing an additional re-render with the `fetchMore` result by
+        // itself. By wrapping in `setTimeout`, this should provide a short
+        // delay to allow the `QueryInfo.notify` handler to run before this
+        // promise is checked.
+        // See https://github.com/apollographql/apollo-client/issues/11315 for
+        // more information
+        setTimeout(() => {
+          if (this.promise.status === "pending") {
+            this.result = result;
+            this.resolve?.(result);
+          }
+        });
       })
       .catch(() => {});
 

src/testing/internal/scenarios/index.ts

@@ -80,8 +80,8 @@ export interface PaginatedCaseVariables {
 export function setupPaginatedCase() {
   const query: TypedDocumentNode<PaginatedCaseData, PaginatedCaseVariables> =
     gql`
-      query letters($limit: Int, $offset: Int) {
-        letters(limit: $limit) {
+      query LettersQuery($limit: Int, $offset: Int) {
+        letters(limit: $limit, offset: $offset) {
           letter
           position
         }