Daraio, Simar and Wilson separability test (2018) in the second stage efficiency analysis

[Pedro Cantos]

Rencently the analysis of external (context) variables on a typical second-stage effyciency analysis requires to know if these variables affect not only the efficiency distribution but also the production possibility set. Daraio, Simar and Wilson (The econometrics journal, 2018) propose a separability test where this fact is tested. Only when separability conditions is positively tested, the second stage efficiency analysis makes sense. I would appreciate a lot if someone knows if this tests has been coded in Stata, or how could be coded. Thanks in advance