This test is for becoming a citizen not to get a visa to join spouse or father. They will need to go through the Interview process and satidfy the officer that they will be able to adjust here. There are no specific requirement for family members to join but you should check with Home office.

They will need to pass the test when they want to become a citizen.

Hope this answer yor question.

does my wife and my 15 years old kid need to pass the uk test for the british nationality even if i become a british citizenship?

Your 15 yr old wont need to take the test but I think your wife will have to take the test as well.  My husband is a british citizen and I had to take the test,  but my two children of 16 and 13 do not have to take the test.