title: Apollo MockedProvider cannot return data using useLazyQuery with onCompleted
body: <p>I am using Apollo Client (3.3.16) MockedProvider and Jest + react testing library to test a component which using useLazyQuery with onCompleted attribute. However, MockedProvider cannot call the onCompleted function (handleData() in my case). After the console.log I found that the onCompleted function has never been triggered. Any ideas how to test component (  in my case)  with useLazyQuery? Appreciated in advance!
  My react component code is like this:</p>
  <pre><code>const handleData = data =&gt; { // this function never been called for testing
      setData(data.dataWithFilters.data);
    };
  
    const [loadData, { loading }] = useLazyQuery(
      GET_DATA,
      {
        variables: {
          id: productId,
          first: 999999,
          page: 1,
          isBase: true
        },
        onCompleted: handleData, // never been triggered for testing
        fetchPolicy: &quot;network-only&quot;
      }
    );
  
    useEffect(() =&gt; { // works fine
      loadData({
         variables: {
          id: productId,
          first: 999999,
          page: 1,
          isBase: true
        },
        fetchPolicy: &quot;network-only&quot;
      });
    }, [loadData, productId]); 
  </code></pre>
  <p>My testing code is:</p>
  <pre><code> const renderComponent = (mocksData) =&gt; {
      render(
        &lt;MockedProvider
          mocks={mocksData}
          defaultOptions={{
            query: { fetchPolicy: &quot;no-cache&quot; },
            watchQuery: { fetchPolicy: 'no-cache' },
          }}
          addTypename={false}
        &gt;
          &lt;ServicesContextProvider freightRateServices={{}}&gt;
            &lt;ContractInformationPageProvider&gt;
              &lt;MemoryRouter initialEntries={[&quot;contracts/311&quot;]}&gt;
                &lt;Route path=&quot;products/:productId&quot;&gt;
                  &lt;ContractInformationPage /&gt;
                &lt;/Route&gt;
              &lt;/MemoryRouter&gt;
            &lt;/ContractInformationPageProvider&gt;
          &lt;/ServicesContextProvider&gt;
        &lt;/MockedProvider&gt;,
        {
          wrapper: BrowserRouter
        }
      );
    };
  </code></pre>