fix: queryDeduplication from context

[igaloly]

Overview
As mentioned in this article, https://www.apollographql.com/docs/react/networking/network-layer/#query-deduplication, if we want to override our default queryManager's queryDeduplication property, we should pass to request's context { queryDeduplication: boolean }.

The problem
It seems like getObservableFromLink did not handle the property from the context and just passed { forceFetch: [arg queryDeduplication / default queryDeduplication] }

The solution
Make getObservableFromLink's deduplication smarter

    if(typeof deduplication === 'undefined') { // else, is passed as an argument
      if(typeof context === 'object' && 'queryDeduplication' in context) {
        deduplication = context.queryDeduplication
      } else {
        deduplication = this.queryDeduplication
      }
    }

Issues
apollographql/apollo-link#517
#4150
https://github.com/apollographql/apollo-feature-requests/issues/40

Edit
It seems like tests are failing because of the use of private class properties.
Those properties were changes and that's why they need to be tested.

[Kalcode]

Looking into passing this for context per query rather than disabling it client wide.

Do we know what the status on getting this merged?

Thanks

[Kalcode]

Looking to disable deduplication per request on hooks and refetch queries.

Per documentation

Query deduplication can help reduce the number of queries that are sent over the wire. It is turned on by default, but can be turned off by passing queryDeduplication: false to the context on each requests or using the defaultOptions key on Apollo Client setup.

Do we know the status on when this will get merged?

Thanks

[benjamn]

Thanks for your patience @igaloly—this definitely fell through the cracks as we were working on AC3. I made a small change to the default logic (have a look if you're curious), and I was able to fix the tests by cherry-picking @Kujawadl's commit from #6526, so this seems ready to go.

[benjamn]

Heads up: we're not quite ready to publish @apollo/client@3.1.0 yet, but I've published an @apollo/client@3.1.0-pre.0 release that includes this PR, if you want to try that in the meantime. 🙏

[benjamn]

Following up: we just published @apollo/client@3.1.0 to npm!