How can I mock a paginated GraphQL query? - unit-testing

Question

I am using apollo/client and graphql-tools/mock to auto mock graphql queries and test React Native components that use them. My schema is generated from an introspection query created by graphql-codegen. For the most part, my queries are getting mocked by addMocksToSchema just fine. However I have a query that is not returning any mock data.
The query is paginated and doesn't follow the same structure of the examples in the docs (https://www.graphql-tools.com/docs/mocking). Instead of having a query with a node that has a field that is a connection type, the connection is returned from the query. This means I can't use relayStylePaginationMock to mock my function because the resolver argument of addMocksToSchema expects the nodes to be objects not functions(function is the return type of relayStylePaginationMock).
In the below code I have tried overriding the newsPost query with a resolver, but I can't figure out how to get the NewsPostEdges from the store and put them in my mock. Everything I have tried has broken the mock and caused it to return undefined for the whole mocked query.
Why does a paginated mock not work by default?
How can I mock this query?
Schema:
type Query {
newsPost: NewsPostConnection
}
type NewsPostConnection {
totalCount: Int
edges: [NewsPostEdge]!
pageInfo: PageInfo!
}
type NewsPostEdge {
node: NewsPostNode
cursor: String!
}
type NewsPostNode {
newsPostId: Int!
isPinned: Boolean!
label: String
title: String
content: String
postType: NewsPostType!
createdDate: DateTime
createdDateTime: String
creator: UserNode!
}
type PageInfo {
hasNextPage: Boolean!
hasPreviousPage: Boolean!
endCursor: String
startCursor: String
}
News Posts query:
query NewsPosts(
$after: String
$first: Int
$newsPostId: Filter_ID
$sort: [NewsPostSortEnum]
$isPinned: Filter_Boolean
) {
newsPosts(
after: $after
first: $first
newsPostId: $newsPostId
sort: $sort
isPinned: $isPinned
) {
pageInfo {
hasNextPage
endCursor
}
edges {
post: node {
newsPostId
postType
isPinned
label
createdDateTime
creator {
initials
avatarUrl
displayName
}
content
}
}
}
}
newsPostsContent.test.tsx
import React from 'react';
import { waitFor } from '#testing-library/react-native';
import { PartialDeep } from 'type-fest';
import { faker } from '#faker-js/faker';
import { createFakeUser, render } from '#root/unit-tests/#util';
import { NewsPostNode, NewsPostType } from '#root/src/generated';
import NewsPostContent from '../NewsPostContent';
const mocks = {
NewsPostNode: (): PartialDeep<NewsPostNode> => {
const postId = faker.random.numeric(4);
const createdDate = faker.date.recent(10);
return {
postId,
isPinned: true,
label: 'test',
content: `<div><p>${faker.random.words(10)}</p></div>`,
postType: NewsPostType.Announcement,
createdDate: createdDate.toISOString(),
createdDateTime: createdDate.toISOString(),
};
},
UserNode: createUserPerson(),
};
describe('Dashboard News', () => {
it('renders dashboard news', async () => {
const { getByTestId, debug } = render(
<NewsPostContent />,
mocks,
);
await waitFor(() => [debug(), expect(getByTestId('newsPostContent:Card')).toBeDefined()]);
});
});
NewsPostsContetnt.tsx
const NewsPostContent = () => {
const [newsPostList, setNewsPostList] = useState<PartialDeep<NewsPostNode>[]>([])
const {
data,
loading,
refetch: refetchPosts,
} = useNewsPostsQuery({
variables: { first: MAX_POSTS, isPinned: true, sort: [PostSortEnum.CreatedDateDesc] },
});
console.log(data); // <-- returns undefined when mock breaks
useEffect(() => {
const newsPostEdges = data?.newsPosts?.edges ?? [];
const newsPostNodes = newsPostEdges.reduce((posts, newsPostNode) => {
if (newsPostNode?.post) {
posts.push(newsPostNode.post);
}
return posts;
}, [] as PartialDeep<NewsPostNode>[]);
setNewsPostList(newsPostNodes);
}, [data]);
return (
{<View>
// Component UI to render posts
</View>}
)
}
AutoMockedProvider.tsx
import React from 'react';
import { ApolloProvider, ApolloClient, InMemoryCache } from '#apollo/client';
import { buildClientSchema } from 'graphql';
import {
addMocksToSchema,
createMockStore,
IMocks,
IMockStore,
relayStylePaginationMock,
} from '#graphql-tools/mock';
import { SchemaLink } from '#apollo/client/link/schema';
import { faker } from '#faker-js/faker';
const introspectionResult = require('../../src/generated/introspection.json');
const defaultMocks = {
Date: () => faker.date.recent().toISOString(),
DateTime: () => faker.date.recent().toISOString(),
};
const resolvers = (store: IMockStore) => ({
Query: {
newsPosts: (root, { isPinned, after, first, postId, sort }) => {
return {
edges: (ref) => {
const connectionsRef = store.get('NewsPostConnection');
const edgesRef = store.get(connectionsRef, 'edges');
return edgesRef; // <-- this breaks the mock
},
pageInfo: {
endCursor: null,
hasNextPage: false,
},
};
},
},
});
const AutoMockedProvider = ({
mocks = {},
children,
}: React.PropsWithChildren<{ mocks?: IMocks }>) => {
const schema = buildClientSchema(introspectionResult);
const store = createMockStore({ mocks: { ...defaultMocks, ...mocks }, schema });
const schemaWithMocks = addMocksToSchema({
schema,
mocks: {
...defaultMocks,
...mocks,
},
resolvers,
preserveResolvers: false,
store,
});
const client = new ApolloClient({
link: new SchemaLink({ schema: schemaWithMocks }),
cache: new InMemoryCache(),
});
return <ApolloProvider client={client}>{children}</ApolloProvider>;
};
export default AutoMockedProvider;