Wait On Received Actions To Facilitate Snapshot Testing

[TicTocCroc]

We use TCA in our application, and we make use of extensive image-based snapshot tests in our test suite.

Many of our screens have multi-step loading processes before they are completely loaded and ready to snapshot. And some of our screens even render intermediate states during the loading process, so there are several loading snapshots we'd like to capture.

These tests usually rely on the wait snapshot strategy to wait an arbitrary amount of time before capturing the snapshot. But this strategy is imprecise, and often fails to capture the view when it's in a known good state for testing.

A facility to wait on received actions on a regular store (similar to TestStore) would help us wait for our loading processes to finish, and ensure that we are capturing the screen in the state we intended.

Alternatively, TestStore could expose a regular Store that we could use to drive our view renders.

I took a shot at implementing this myself, but the complexity of TestStore defeated me.