This is a crazy project to implement the gameplay of 5D Chess With Multiverse Timetravel in SQL.
Also I made a small custom test framework in Ruby. The code defining the test macro is brutal but the tests themselves are straightforward. Each test is of the following form:
name --- the sequence of movements from (w,x,y,z) to (w,x,y,z) from (w,x,y,z) to (w,x,y,z) ... --- an assertion query