clearStore() works differently than resetStore() - clears cache after callbacks

[ds8k]

Intended outcome:
clearStore() should clear the existing cache and then execute the onClearStore callbacks

Actual outcome:
clearStore() runs the onClearStore callbacks and then clears the cache, negating any operations that were performed within said callbacks.

How to reproduce the issue:

const unsubscribe = client.onClearStore(() => {
  client.writeData({ data: { value: 'test' } })
})

client.clearStore()
console.log(client.extract()) // cache is empty

Looking at the code for clearStore shows exactly why this is happening:

public clearStore(): Promise<void | null> {
  const { queryManager } = this;
  return Promise.resolve()
    .then(() => Promise.all(this.clearStoreCallbacks.map(fn => fn()))) // callbacks are fired first
    .then(
      () =>
        queryManager ? queryManager.clearStore() : Promise.resolve(null), // then the store is cleared
    );
}

resetStore works the way I would expect it to:

public resetStore(): Promise<ApolloQueryResult<any>[] | null> {
  return Promise.resolve()
    .then(() => {
      return this.queryManager
        ? this.queryManager.clearStore() // the store is cleared
        : Promise.resolve(null);
    })
    .then(() => Promise.all(this.resetStoreCallbacks.map(fn => fn()))) // then the callbacks are run
    .then(() => {
      return this.queryManager && this.queryManager.reFetchObservableQueries
        ? this.queryManager.reFetchObservableQueries()
        : Promise.resolve(null);
    });
}

Versions

  System:
    OS: macOS 10.14.3
  Binaries:
    Node: 8.13.0 - ~/.nvm/versions/node/v8.13.0/bin/node
    Yarn: 1.15.2 - ~/.yarn/bin/yarn
    npm: 6.4.1 - ~/.nvm/versions/node/v8.13.0/bin/npm
  Browsers:
    Chrome: 73.0.3683.103
    Safari: 12.0.3
  npmPackages:
    apollo-boost: 0.3.1 => 0.3.1 
    apollo-cache-inmemory: 1.3.11 => 1.3.11 
    apollo-cache-persist: 0.1.1 => 0.1.1 
    react-apollo: 2.5.4 => 2.5.4