What tests are appropriate?

[sdmccabe]

In conversations, there are a few constraints that are possible to test:

1. Enforcing return types (if you pass a DiGraph, you shouldn't get Graph back).
2. Enforcing equal numbers of nodes and edges after rewiring.
3. Does the algorithm handle the empty graph and the complete graph correctly?

In general, these algorithms are going to be highly nondeterministic, which presents a challenge for testing them. But ideally we can come up with some things that cover most rewirers (even if we have to have exceptions).