Recipe for easy testing of event projections

[jeremydmiller]

This has come up a couple times. Might be mostly documentation, but let's think about it.

[jeremydmiller]

I do actually have some ideas here. Wanna do something similar to what Alba does for testing HTTP endpoints -- which was lifted out of FubuMVC's old mechanism for testing its own behavior.

What we need:

• Reusable harness based on an IHost setup
• Harness can wipe out event state and the related state for projected documents on demand
• Allows you to very quickly throw events at new streams. Let the user define multiple batches of events to simulate capturing events at different times
• Declarative assertions for a document being deleted, existing, or being archived
• Declarative helper to assert data changes on a persisted document, but let's you mostly use the assertion library of your choice
• Declarative helper to assert that a document w/ a given identity & type exists or was deleted