Question on Traps & Snares

The rule reads:

Any enemy model that ends its charge move in base contact with a model with this special rule must make a Dangerous Terrain test.

So I wondered how this interacts with the rules for formation units charging skirmishers?

Does the process of the skirmishers (gnoblar trappers) forming into ranks when charged happen during the "charge move"? Otherwise in most cases there would only be one dangerous terrain test, since the charging unit stops when it impacts a single skirmisher.