test-utils: allow passing a custom cache object to MockedProvider

Changelog.md

@@ -24,6 +24,9 @@
   to see if any query errors have occurred. A better (and supported) way to
   check for errors is to use the result `errors` property. <br/>
   [@TLadd](https://github.com/TLadd) in [#1983](https://github.com/apollographql/react-apollo/pull/1983)
+- Allow a custom `cache` object to be passed into the test-utils
+  `MockedProvider`.  <br/>
+  [@palmfjord](https://github.com/palmfjord) in [#2254](https://github.com/apollographql/react-apollo/pull/2254)
 
 ## 2.1.11 (August 9, 2018)
 

src/test-utils.tsx

@@ -5,12 +5,14 @@ import { InMemoryCache as Cache } from 'apollo-cache-inmemory';
 
 import { ApolloProvider } from './index';
 import { MockedResponse, MockLink } from './test-links';
+import { ApolloCache } from 'apollo-cache';
 export * from './test-links';
 
-export interface MockedProviderProps {
+export interface MockedProviderProps<TSerializedCache = {}> {
   mocks?: MockedResponse[];
   addTypename?: boolean;
   defaultOptions?: DefaultOptions;
+  cache?: ApolloCache<TSerializedCache>;
 }
 
 export interface MockedProviderState {
@@ -25,9 +27,9 @@ export class MockedProvider extends React.Component<MockedProviderProps, MockedP
   constructor(props: MockedProviderProps) {
     super(props);
 
-    const { mocks, addTypename, defaultOptions } = this.props;
+    const { mocks, addTypename, defaultOptions, cache } = this.props;
     const client = new ApolloClient({
-      cache: new Cache({ addTypename }),
+      cache: cache || new Cache({ addTypename }),
       defaultOptions,
       link: new MockLink(mocks || [], addTypename),
     });

test/test-utils.test.tsx

@@ -121,6 +121,28 @@ it('allows for querying with the typename', done => {
   );
 });
 
+it('allows for using a custom cache', done => {
+  const cache = new InMemoryCache();
+  cache.writeQuery({
+    query,
+    variables,
+    data: { user },
+  });
+
+  const Container: React.SFC<ChildProps<Variables, Data, Variables>> = props => {
+    expect(props.data).toMatchObject({ user });
+    done();
+
+    return null;
+  };
+  const ContainerWithData = withUser(Container);
+  renderer.create(
+    <MockedProvider mocks={[]} cache={cache}>
+      <ContainerWithData {...variables} />
+    </MockedProvider>,
+  );
+});
+
 it('errors if the variables in the mock and component do not match', done => {
   class Container extends React.Component<ChildProps<Variables, Data, Variables>> {
     componentWillReceiveProps(nextProps: ChildProps<Variables, Data, Variables>) {
@@ -317,6 +339,7 @@ it('doesnt crash on unmount if there is no query manager', () => {
       return null;
     }
   }
+
   renderer
     .create(
       <MockedProvider>