Add/fix failing test of reading cache data immediately during server-side rendering.

CHANGELOG.md

@@ -5,6 +5,9 @@
 - Increment `queryInfo.lastRequestId` only when making a network request through the `ApolloLink` chain, rather than every time `fetchQueryByPolicy` is called. <br/>
   [@dannycochran](https://github.com/dannycochran) in [#7956](https://github.com/apollographql/apollo-client/pull/7956)
 
+- During server-side rendering, allow initial `useQuery` calls to return final `{ loading: false, data }` results when the cache already contains the necessary data. <br/>
+  [@benjamn](https://github.com/benjamn) in [#7983](https://github.com/apollographql/apollo-client/pull/7983)
+
 ## Apollo Client 3.3.14
 
 ### Improvements

src/react/data/QueryData.ts

@@ -175,20 +175,13 @@ export class QueryData<TData, TVariables> extends OperationData<
       return ssrLoading;
     }
 
-    let result;
     if (this.ssrInitiated()) {
-      if (skip) {
-        result = this.getQueryResult();
-      } else {
-        result =
-          this.context.renderPromises!.addQueryPromise(
-            this,
-            this.getQueryResult
-          ) || ssrLoading;
-      };
+      const result = this.getQueryResult() || ssrLoading;
+      if (result.loading && !skip) {
+        this.context.renderPromises!.addQueryPromise(this, () => null);
+      }
+      return result;
     }
-
-    return result;
   }
 
   private prepareObservableQueryOptions() {

src/react/ssr/__tests__/__snapshots__/useQuery.test.tsx.snap

@@ -0,0 +1,49 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`useQuery Hook SSR should return data written previously to cache during SSR pass if using cache-only fetchPolicy 1`] = `
+Object {
+  "Order:{\\"selection\\":\\"RELEVANCE\\"}": Object {
+    "__typename": "Order",
+    "selection": "RELEVANCE",
+  },
+  "ROOT_QUERY": Object {
+    "__typename": "Query",
+    "getSearchResults": Object {
+      "__typename": "SearchResults",
+      "locale": "en-US",
+      "order": Object {
+        "__ref": "Order:{\\"selection\\":\\"RELEVANCE\\"}",
+      },
+      "pagination": Object {
+        "pageLimit": 3,
+      },
+      "results": Array [
+        Object {
+          "__ref": "SearchResult:1",
+        },
+        Object {
+          "__ref": "SearchResult:2",
+        },
+        Object {
+          "__ref": "SearchResult:3",
+        },
+      ],
+    },
+  },
+  "SearchResult:1": Object {
+    "__typename": "SearchResult",
+    "id": 1,
+    "text": "hi",
+  },
+  "SearchResult:2": Object {
+    "__typename": "SearchResult",
+    "id": 2,
+    "text": "hello",
+  },
+  "SearchResult:3": Object {
+    "__typename": "SearchResult",
+    "id": 3,
+    "text": "hey",
+  },
+}
+`;

src/react/ssr/__tests__/useQuery.test.tsx

@@ -5,7 +5,7 @@ import { MockedProvider, mockSingleLink } from '../../../testing';
 import { ApolloClient } from '../../../core';
 import { InMemoryCache } from '../../../cache';
 import { ApolloProvider } from '../../context';
-import { useQuery } from '../../hooks';
+import { useApolloClient, useQuery } from '../../hooks';
 import { render, wait } from '@testing-library/react';
 import { renderToStringWithData } from '..';
 
@@ -195,4 +195,96 @@ describe('useQuery Hook SSR', () => {
       expect(result).toBe('');
     });
   });
+
+  it('should return data written previously to cache during SSR pass if using cache-only fetchPolicy', async () => {
+    const cache = new InMemoryCache({
+      typePolicies: {
+        Order: {
+          keyFields: ["selection"],
+        },
+      },
+    });
+
+    const query = gql`
+      query GetSearchResults {
+        getSearchResults @client {
+          locale
+          order {
+            selection
+          }
+          pagination {
+            pageLimit
+          }
+          results {
+            id
+            text
+          }
+        }
+      }
+    `;
+
+    const initialData = {
+      getSearchResults: {
+        __typename: 'SearchResults',
+        locale: 'en-US',
+        order: {
+          __typename: 'Order',
+          selection: 'RELEVANCE',
+        },
+        pagination: {
+          pageLimit: 3,
+        },
+        results: [
+          { __typename: "SearchResult", id: 1, text: "hi" },
+          { __typename: "SearchResult", id: 2, text: "hello" },
+          { __typename: "SearchResult", id: 3, text: "hey" },
+        ],
+      },
+    };
+
+    const spy = jest.fn();
+
+    const Component = () => {
+      useApolloClient().writeQuery({ query, data: initialData });;
+
+      const { loading, data } = useQuery(query, {
+        fetchPolicy: 'cache-only',
+      });
+
+      spy(loading);
+
+      if (!loading) {
+        expect(data).toEqual(initialData);
+
+        const {
+          getSearchResults: {
+            pagination: {
+              pageLimit,
+            },
+          },
+        } = data;
+        return (
+          <div>
+            {pageLimit}
+          </div>
+        );
+      }
+      return null;
+    };
+
+    const app = (
+      <MockedProvider
+        addTypename
+        cache={cache}
+      >
+        <Component />
+      </MockedProvider>
+    );
+
+    return renderToStringWithData(app).then(markup => {
+      expect(spy).toHaveBeenNthCalledWith(1, false);
+      expect(markup).toMatch(/<div.*>3<\/div>/);
+      expect(cache.extract()).toMatchSnapshot();
+    });
+  });
 });