Call nextFetchPolicy with "variables-changed" even if there is a fetchPolicy option specified. (#11626)

* Call `nextFetchPolicy` with "variables-changed" even if there is a `fetchPolicy` specified.
fixes #11365

* update size-limits

* remove `.only`

* Clean up Prettier, Size-limit, and Api-Extractor

* use `mockFetchQuery` helper in test

* fix detail in test-tsconfig.json

---------

Co-authored-by: phryneas <[email protected]>

Author: phryneas

Diff for: .changeset/tasty-chairs-dress.md

@@ -0,0 +1,5 @@
+---
+"@apollo/client": patch
+---
+
+Call `nextFetchPolicy` with "variables-changed" even if there is a `fetchPolicy` specified. (fixes #11365)

Diff for: .size-limits.json

@@ -1,4 +1,4 @@
 {
-  "dist/apollo-client.min.cjs": 39906,
-  "import { ApolloClient, InMemoryCache, HttpLink } from \"dist/index.js\" (production)": 32896
+  "dist/apollo-client.min.cjs": 39924,
+  "import { ApolloClient, InMemoryCache, HttpLink } from \"dist/index.js\" (production)": 32903
 }

Diff for: src/core/ObservableQuery.ts

@@ -910,7 +910,10 @@ Did you mean to call refetch(variables) instead of refetch({ variables })?`,
         options.fetchPolicy !== "standby" &&
         // If we're changing the fetchPolicy anyway, don't try to change it here
         // using applyNextFetchPolicy. The explicit options.fetchPolicy wins.
-        options.fetchPolicy === oldFetchPolicy
+        (options.fetchPolicy === oldFetchPolicy ||
+          // A `nextFetchPolicy` function has even higher priority, though,
+          // so in that case `applyNextFetchPolicy` must be called.
+          typeof options.nextFetchPolicy === "function")
       ) {
         this.applyNextFetchPolicy("variables-changed", options);
         if (newNetworkStatus === void 0) {

Diff for: src/react/hooks/__tests__/useQuery.test.tsx

@@ -11,6 +11,7 @@ import {
   OperationVariables,
   TypedDocumentNode,
   WatchQueryFetchPolicy,
+  WatchQueryOptions,
 } from "../../../core";
 import { InMemoryCache } from "../../../cache";
 import { ApolloProvider } from "../../context";
@@ -36,6 +37,7 @@ import {
 } from "../../../testing/internal";
 import { useApolloClient } from "../useApolloClient";
 import { useLazyQuery } from "../useLazyQuery";
+import { mockFetchQuery } from "../../../core/__tests__/ObservableQuery";
 
 const IS_REACT_17 = React.version.startsWith("17");
 
@@ -7071,6 +7073,131 @@ describe("useQuery Hook", () => {
 
       expect(reasons).toEqual(["variables-changed", "after-fetch"]);
     });
+
+    it("should prioritize a `nextFetchPolicy` function over a `fetchPolicy` option when changing variables", async () => {
+      const query = gql`
+        {
+          hello
+        }
+      `;
+      const link = new MockLink([
+        {
+          request: { query, variables: { id: 1 } },
+          result: { data: { hello: "from link" } },
+          delay: 10,
+        },
+        {
+          request: { query, variables: { id: 2 } },
+          result: { data: { hello: "from link2" } },
+          delay: 10,
+        },
+      ]);
+
+      const client = new ApolloClient({
+        cache: new InMemoryCache(),
+        link,
+      });
+
+      const mocks = mockFetchQuery(client["queryManager"]);
+
+      const expectQueryTriggered = (
+        nth: number,
+        fetchPolicy: WatchQueryFetchPolicy
+      ) => {
+        expect(mocks.fetchQueryByPolicy).toHaveBeenCalledTimes(nth);
+        expect(mocks.fetchQueryByPolicy).toHaveBeenNthCalledWith(
+          nth,
+          expect.anything(),
+          expect.objectContaining({ fetchPolicy }),
+          expect.any(Number)
+        );
+      };
+      let nextFetchPolicy: WatchQueryOptions<
+        OperationVariables,
+        any
+      >["nextFetchPolicy"] = (_, context) => {
+        if (context.reason === "variables-changed") {
+          return "cache-and-network";
+        } else if (context.reason === "after-fetch") {
+          return "cache-only";
+        }
+        throw new Error("should never happen");
+      };
+      nextFetchPolicy = jest.fn(nextFetchPolicy);
+
+      const { result, rerender } = renderHook<
+        QueryResult,
+        {
+          variables: { id: number };
+        }
+      >(
+        ({ variables }) =>
+          useQuery(query, {
+            fetchPolicy: "network-only",
+            variables,
+            notifyOnNetworkStatusChange: true,
+            nextFetchPolicy,
+          }),
+        {
+          initialProps: {
+            variables: { id: 1 },
+          },
+          wrapper: ({ children }) => (
+            <ApolloProvider client={client}>{children}</ApolloProvider>
+          ),
+        }
+      );
+      // first network request triggers with initial fetchPolicy
+      expectQueryTriggered(1, "network-only");
+
+      await waitFor(() => {
+        expect(result.current.networkStatus).toBe(NetworkStatus.ready);
+      });
+
+      expect(nextFetchPolicy).toHaveBeenCalledTimes(1);
+      expect(nextFetchPolicy).toHaveBeenNthCalledWith(
+        1,
+        "network-only",
+        expect.objectContaining({
+          reason: "after-fetch",
+        })
+      );
+      // `nextFetchPolicy(..., {reason: "after-fetch"})` changed it to
+      // cache-only
+      expect(result.current.observable.options.fetchPolicy).toBe("cache-only");
+
+      rerender({
+        variables: { id: 2 },
+      });
+
+      expect(nextFetchPolicy).toHaveBeenNthCalledWith(
+        2,
+        // has been reset to the initial `fetchPolicy` of "network-only" because
+        // we changed variables, then `nextFetchPolicy` is called
+        "network-only",
+        expect.objectContaining({
+          reason: "variables-changed",
+        })
+      );
+      // the return value of `nextFetchPolicy(..., {reason: "variables-changed"})`
+      expectQueryTriggered(2, "cache-and-network");
+
+      await waitFor(() => {
+        expect(result.current.networkStatus).toBe(NetworkStatus.ready);
+      });
+
+      expect(nextFetchPolicy).toHaveBeenCalledTimes(3);
+      expect(nextFetchPolicy).toHaveBeenNthCalledWith(
+        3,
+        "cache-and-network",
+        expect.objectContaining({
+          reason: "after-fetch",
+        })
+      );
+      // `nextFetchPolicy(..., {reason: "after-fetch"})` changed it to
+      // cache-only
+      expect(result.current.observable.options.fetchPolicy).toBe("cache-only");
+    });
   });
 
   describe("Missing Fields", () => {

Diff for: src/tsconfig.json

@@ -5,6 +5,8 @@
 {
   "compilerOptions": {
     "noEmit": true,
+    "declaration": false,
+    "declarationMap": false,
     "lib": ["es2015", "esnext.asynciterable", "ES2021.WeakRef"],
     "types": ["jest", "node", "./testing/matchers/index.d.ts"]
   },