I have a mole on my thigh and i'm worried that it'll turn into cancer. what kind of tests do i need?

See a dermatologist: Dermatologists are the most highly trained docs to examine skin lesions and determine if they are suspicious. If suspicious, the doc will do a biopsy. Avoid a biopsy by a non-dermatologist - they may not take a wide enough excision.

Biopsy or removal: If you have a mole that is worrisome for cancer, it needs to be removed or biopsied. Most moles are small enough that the biopsy is a removal of the mole. The mole will then be sent to pathology to be tested.