What is the best pregnancy test/ advice?

my little brothers girlfriend is telling everyone sheis pregnant, i have yet to see proof, she is 15!!!! i found out bc a girl i went to school with (i am 21 my brother just turned 18) said "congrats auntie" she saw on the15yos facebook her statuss over thepast week saying "morning sickness gotta get use to it" "being sick is going to be well worth it" "my back and bally hurt" "im so excited to feel it move" like come on at15 she should be ashamed and sad and angry right? do you thinkshe is just trying to hold onto mybrother? i need to know theeee best/ most accurate testto buy so she can take it infront of me... im disgusted by this girl even if she is why post before telling family?!?! thats messed up right? my brother and iare very close this will ruin that....