化學 alkane and alkene 問題

Test 1 :
Shake the unknown with bromine solution. Alkenes can decolorize the brown bromine solution, but alkanes cannot.

Test 2 :
Shake the unknown with acidified potassium permanganate solution. Alkenes can decolorize the purple permanganate solution, but alkanes cannot.

I think Test 1 has some problem.
Test 1 should be done in the absence of light.
(Both alkane and alkene can decolorize Br2 under light)

by adding Cl2 or Br2
only can react with alkanes