I found out the solution, when i unlocked the solutions. You need to return more than just resultObj. You shoud return {factor: resultObj}

Yes. In that test a should be [1, 2, 3]. You probably set your methods to modify vector itself, so in previous test your vector changed itself while it should not have.

Cannot pass one of the substraction tests;
a:[4, 6, 8] b:[3, 4, 5 ]
Expected:[-2,-2,-2]
But it should be [1, 2, 3]
I am missing something?

Test case works okay but when i try to submit it with the same values from test case which is {"13":1} i get undefined.