Enable optimistic read of cache using client

[jer-sen]

To fix this issue : #2222

Tests and doc should be updated...

[jbaxleyiii]

@Jay1337 great start! Adding tests for this should be able to be done following the patterns here and here

Let me know if you have any questions!

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions to Apollo Client!

[jer-sen]

Hey !

[jbaxleyiii]

@Jay1337 are you able to finish this? Or do you need me to? I'd love to get this shipped!

[jer-sen]

Honestly I don't know when I will have time for that. If you can do it... I think it would take you far less time than what it would take me.

[jbaxleyiii]

@Jay1337 no worries! Thank you so much for all that you have already done for the 2.0 line! It wouldn't be nearly what it is without your investigations and help! I'll happily pick this up and get it shipped!

[jer-sen]

@jbaxleyiii Thanks :)

[jbaxleyiii]

@Jay1337 I'm going to close this one down and open it back up when I have some time to bring it in!

[danielgreane]

Hey,
What other work was needed on this? Seems to be working
We have a few places in our codebase where we depend on optimistic fragment and query reads (for offline support), I've run this PR locally and seems to be working fine. Is it just regression that's blocking it from being merged?

[apollo-cla]

	Warnings
⚠️	❗ Big PR

Generated by 🚫 dangerJS

[hwillson]

Thanks for you work on this @Jay1337 - we're all set here. LGTM!

[jer-sen]

@hwillson you're welcome !