Grid tests

[aswinpvijayan]

It would be good to port the docs for synthesizer grids here as part of testing to see if things are consistent, so on pull requests the changes are compared against those, to ensure that they work.

[WillJRoper]

Seconded, in an ideal world we would generate a toy grid during testing and feed this through the relevant tests.

Another way to achieve this would just be thorough unit testing.