Tests: Test Conventions, Fixtures, and Scenario Tests

[seangwright]

The unit test suite doesn't have any conventions around the naming of variables/methods or the descriptions of individual tests. We also don't have any fixtures for common setup.

There are likely many combinations of tests that are missing if we want full coverage of typing support.

I'd also like some more fleshed out scenario tests to show how/prove that all the methods play nice together.