JS : bad Karma, lost data

I want to test some classes (one per module) with dependencies (no ciruclar) in a folder structure like this :

/src
  /chessmen
     Kings.js (extends ../core/Chessman)
     Pawn.js (extends ../core/Chessman)
     ...
  /core
    Board.js (imports Refs)
    Chessman.js (imports Ray)
    Ray.js
    Refs.js
    Sides.js (imports WindRoses.js)
    WindRoses
  /engine
    RayCaster.js

/test
  /chessmen
    ...
  /core
   ...
  /engine
    RayCaster.js (import src/core/ Refs, sides, King, Queen, board)

The trouble comes when testing with karma + Jasmine + babel preprocessor

If a first test case imports and use, saying, Sides.js or King.js, seems to "eat" or consume the data, in a way that it s impossible to use the imported module in another test case

for example, test/engine/RayCaster imports a Queen module, but it logs with a object {} (empty) in place of function Queen() { ... }

QUESTIONS

What's happening ?

Is it possible to reset imports (or cancel them) between test cases

Since karma imports files alphabetically, it it possible to have a kind of test/index.js which does all imports and call tests in the dependency module order ?