How to skip mocking undefined fields/optional properties

[carrie-reid-knox]

Hello! If this was answered somewhere else already, please point me in the right direction. I was looking at Issue 930 and Issue 1068, but couldn't find exactly what I was looking for.

I am looking for a way to have addMocksToSchema not mock optional properties that are not supplied.

Here is my test provider that I have created:

export const ApolloTestProvider = (props: ApolloTestProviderProps) => {
  const cache = new InMemoryCache();

  const executableSchema = addMocksToSchema({
    schema, // This is my introspection.json
    mocks: {
      ...Mocks,
      ...(props.graphqlMocks || {}),
    },
  });

  const client = new ApolloClient({
    link: new SchemaLink({schema: executableSchema}),
    cache,
  });

  return <ApolloProvider client={client}>{props.children}</ApolloProvider>;
};

In the above example, Mocks is:

const Mocks: IMocks = {
  UUID: () => v4(),
  USD: () => '1.99',
  Date: () => newMockDate(),
  Timestamp: () => '2018-07-13T20:56:00.077448Z',
  String: () => {
    // An custom function to return a random string
  },
};

In the above example, props.graphqlMocks is:

const mocks = {
  Query: () => ({
    me: {
      __typename: 'User',
      id: '1234,
      first_name: 'Jane',
      last_name: 'Doe',
    },
  }),
};

The Typescript type for User (which is the object we are mocking above) is:

User {
  __typename: 'User';
  first_name: Scalars['String'];
  id: Scalars['String'];
  last_name: Scalars['String'];
  member?: Member;
}

The User type has an optional property member which can either be a Member object or undefined. If I do not explicitly pass member: null in my mocks, then a Member object will be mocked. How can I ensure that any optional property that is not supplied remains undefined instead of being provided with a mocked value? Thank you!