This is a perfect - honestly, just perfect - time to use BDD.

You know what you want the code to do. You can write code - use Cucumber. Right now this is the link

Have a look at it - effectively it lets you define the steps for a successful teset, and then then developer goes and writes code that hooks into this definition.

You can then rest assured that whatever the devs have come up with works. Its also exactly what Cucumber proports to do (only it never does, because business people don't write code nor use things with an ugly UI - and who can blame them?)

I don't know if a cucumber port exists for "R", that would be neat you could have the one cucumber spec file and then have both codebases test against it - but i'm sure you could get your guys to just "call" your R code from C# and use that as input to the Cucumber code.

This is a perfect - honestly, just perfect - time to use BDD.

You know what you want the code to do. You can write code - use Cucumber. Right now this is the link

Have a look at it - effectively it lets you define the steps for a successful test, and then the developer goes and writes code that hooks into this definition.

You can then rest assured that whatever the devs have come up with works. Its also exactly what Cucumber purports to do (only it never does, because business people don't write code nor use things with an ugly UI - and who can blame them?)

I don't know if a cucumber port exists for "R", that would be neat you could have the one cucumber spec file and then have both codebases test against it - but i'm sure you could get your guys to just "call" your R code from C# and use that as input to the Cucumber code.