Add test that shows a bug when merging deferred results for arrays.

[phryneas]

This bug was brought to my attention by @fernando-apollo. We'll have to discuss how we can best fix this. I bet there are a few cases where this behaviour is really useful.

The bug showcased here is caused by this part of mergeResult:

apollo-client/src/core/QueryInfo.ts

Lines 375 to 383 in ae5091a

	// Detect the first chunk of a deferred query and merge it with existing
	// cache data. This ensures a `cache-first` fetch policy that returns
	// partial cache data or a `cache-and-network` fetch policy that already
	// has full data in the cache does not complain when trying to merge the
	// initial deferred server data with existing cache data.
	} else if ("hasNext" in result && result.hasNext) {
	const diff = this.getDiff();
	result.data = merger.merge(diff.result, result.data);
	}

Checklist:

• If this PR contains changes to the library itself (not necessary for e.g. docs updates), please include a changeset (see CONTRIBUTING.md)
• If this PR is a new feature, please reference an issue where a consensus about the design was reached (not necessary for small changes)
• Make sure all of the significant new logic is covered by tests

[changeset-bot]

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Latest commit: e5136c4

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[github-actions]

size-limit report 📦

Path	Size
dist/apollo-client.min.cjs	37.08 KB (0%)
import { ApolloClient, InMemoryCache, HttpLink } from "dist/main.cjs"	43.51 KB (0%)
import { ApolloClient, InMemoryCache, HttpLink } from "dist/main.cjs" (production)	42.01 KB (0%)
import { ApolloClient, InMemoryCache, HttpLink } from "dist/index.js"	32.61 KB (0%)
import { ApolloClient, InMemoryCache, HttpLink } from "dist/index.js" (production)	31.27 KB (0%)
import { ApolloProvider } from "dist/react/index.js"	1.22 KB (0%)
import { ApolloProvider } from "dist/react/index.js" (production)	1.21 KB (0%)
import { useQuery } from "dist/react/index.js"	4.28 KB (0%)
import { useQuery } from "dist/react/index.js" (production)	4.1 KB (0%)
import { useLazyQuery } from "dist/react/index.js"	4.59 KB (0%)
import { useLazyQuery } from "dist/react/index.js" (production)	4.41 KB (0%)
import { useMutation } from "dist/react/index.js"	2.55 KB (0%)
import { useMutation } from "dist/react/index.js" (production)	2.54 KB (0%)
import { useSubscription } from "dist/react/index.js"	2.24 KB (0%)
import { useSubscription } from "dist/react/index.js" (production)	2.2 KB (0%)
import { useSuspenseQuery } from "dist/react/index.js"	4.62 KB (0%)
import { useSuspenseQuery } from "dist/react/index.js" (production)	4.05 KB (0%)
import { useBackgroundQuery } from "dist/react/index.js"	4.14 KB (0%)
import { useBackgroundQuery } from "dist/react/index.js" (production)	3.56 KB (0%)
import { useReadQuery } from "dist/react/index.js"	3 KB (0%)
import { useReadQuery } from "dist/react/index.js" (production)	2.94 KB (0%)
import { useFragment } from "dist/react/index.js"	2.09 KB (0%)
import { useFragment } from "dist/react/index.js" (production)	2.04 KB (0%)

[jerelmiller]

Converting this to a draft since this contains a reproduction with a failing test.