correctly test for error equality on jest

[phryneas]

I noticed this when working on tests for subscription errors - jest is extremely lax when comparing errors:

https://github.com/jestjs/jest/blob/c04d13d7abd22e47b0997f6027886aed225c9ce4/packages/expect-utils/src/jasmineUtils.ts#L91-L94

  if (a instanceof Error && b instanceof Error) {
    return a.message == b.message;
  }

This means that we probably have hundreds of assertions that do nothing and might just as well be wrong.

This was the code I used to make it work correctly to work on that one test - I imagine before we can merge this we'll have to adjust dozens of tests (or fix bugs that have been hidden by this).

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[github-actions]

size-limit report 📦

Path	Size
dist/apollo-client.min.cjs	39.26 KB (0%)
import { ApolloClient, InMemoryCache, HttpLink } from "dist/main.cjs"	48 KB (0%)
import { ApolloClient, InMemoryCache, HttpLink } from "dist/main.cjs" (production)	45.53 KB (0%)
import { ApolloClient, InMemoryCache, HttpLink } from "dist/index.js"	34.38 KB (0%)
import { ApolloClient, InMemoryCache, HttpLink } from "dist/index.js" (production)	32.23 KB (0%)
import { ApolloProvider } from "dist/react/index.js"	1.26 KB (0%)
import { ApolloProvider } from "dist/react/index.js" (production)	1.24 KB (0%)
import { useQuery } from "dist/react/index.js"	5.24 KB (0%)
import { useQuery } from "dist/react/index.js" (production)	4.31 KB (0%)
import { useLazyQuery } from "dist/react/index.js"	5.71 KB (0%)
import { useLazyQuery } from "dist/react/index.js" (production)	4.79 KB (0%)
import { useMutation } from "dist/react/index.js"	3.62 KB (0%)
import { useMutation } from "dist/react/index.js" (production)	2.85 KB (0%)
import { useSubscription } from "dist/react/index.js"	4.42 KB (0%)
import { useSubscription } from "dist/react/index.js" (production)	3.46 KB (0%)
import { useSuspenseQuery } from "dist/react/index.js"	5.5 KB (0%)
import { useSuspenseQuery } from "dist/react/index.js" (production)	4.16 KB (0%)
import { useBackgroundQuery } from "dist/react/index.js"	5 KB (0%)
import { useBackgroundQuery } from "dist/react/index.js" (production)	3.65 KB (0%)
import { useLoadableQuery } from "dist/react/index.js"	5.07 KB (0%)
import { useLoadableQuery } from "dist/react/index.js" (production)	3.72 KB (0%)
import { useReadQuery } from "dist/react/index.js"	3.39 KB (0%)
import { useReadQuery } from "dist/react/index.js" (production)	3.34 KB (0%)
import { useFragment } from "dist/react/index.js"	2.32 KB (0%)
import { useFragment } from "dist/react/index.js" (production)	2.27 KB (0%)

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[phryneas]

Without this escape hatch, all these errors will only log [ApolloError: message], so we end up with error messages like Got: [ApolloError: message], expected: [ApolloError: message], with no idea on what's actually wrong.

[phryneas]

@alessbell this is probably relevant to you - until now, the ApolloError would be wrapped by another ApolloError inside of ObservableQuery. The link chain should return "plain" errors, they get wrapped later.

[phryneas]

Spoiler: we never did 😅

[jerelmiller]

Really great find! Glad this will give us more confidence in our tests.