Test store dependency binding

[mbrandonw]

This makes it so that the test context is set when constructing the TestStore and in the modify closures of send/receive, and provides a trailing closure initializer for TestStore for customizing dependencies.

This idea came from @crayment in #1613.

[stephencelis]

I know this'll be a trailing closure without argument labels most of the time, but what do you think of:

Suggested change

	updateDependencies: (inout DependencyValues) -> Void = { _ in },
	prepareDependencies: (inout DependencyValues) -> Void = { _ in },

[mbrandonw]

yep that works for me. will update

[stephencelis]

Good changes!

[crayment]

Love it, thanks!!

[crayment]

I just realized receive should probably be updated as well to have the test stores dependencies for updateExpectingResult. Totally overlooked that in my first discussion.

[mbrandonw]

@crayment That should be the case by virtue of the fact that we updated the private function expectedStateShouldMatch, and both send and receive make use of it. Are you seeing otherwise?

We probably should update the test to get coverage on this fact though.

[crayment]

I haven't verified on this branch yet. Still using my helpers. If you give me a bit I can verify, and maybe even PR an update to the test 😄

[mbrandonw]

I did just verify locally with a test and it seems OK. But yes please feel free to PR a test to get coverage.

[crayment]

Done: #1644

Feel free to just close if you like your test updates better though!