As discussed in the team call, we currently don't have much public-facing information about how to use the MockChain. It would be a very useful addition for newcomers, because the testing setup becomes easier: no need to run your own local node, and the tests run much faster.
What I would personally like to see covered:

• what is the MockChain and roughly how it works
• how to set up and run basic tests against it
• how it compares to using the real chain (side-by-side example? ideally some test where it's very easy to swap the mock chain for a real chain)

probably folks have other ideas for what we should include.

cc @Dominik1999