[3.0] Querying data that is already in the cache sets loading to true

[olgertse]

We pre-cache a lot of data in our app so that switching between different screens can be instantaneous - without flickering and loading states.

Intended outcome:
When running some query:

  const {
    loading,
    data
  } = useQuery(SOME_QUERY);

we expect that loading will be false if data is already in the cache (with default or cache-only fetchPolicy).

Actual outcome:
loading is true even when the requested data is in the cache.

I cannot tell if this is expected behaviour or not but it is definitely different from Apollo Client 2.6.

How to reproduce the issue:
I've created a reproduction that demonstrates this issue https://github.com/od1k/apollo-client-issue-1.

master branch contains a reference implementation with Apollo Client 2.6 which works as expected.
Branch 3.0 is updated to use Apollo Client 3 and exhibits the aforementioned behaviour.

Checkout branch 3.0, start the app, verify that the data is in the cache using Apollo DevTools.
Click Show clock speed button. The app will crash and the Console will contain a log showing that loading is set to true.

Verify that the app works as expected with Apollo Client 2.6 by checking out the master branch and repeating the procedure.

Versions

  System:
    OS: macOS 10.15.1
  Binaries:
    Node: 11.10.1 - /usr/local/bin/node
    Yarn: 1.19.1 - /usr/local/bin/yarn
    npm: 6.13.4 - /usr/local/bin/npm
  Browsers:
    Chrome: 79.0.3945.88
    Firefox: 59.0.1
    Safari: 13.0.3
  npmPackages:
    @apollo/client: ^3.0.0-beta.19 => 3.0.0-beta.19 

[benjamn]

This appears to be fixed in the latest version, @apollo/[email protected], likely due to #5791. Please feel free to reopen if the problem persists, and thanks for the reproduction!