It will hurt your career, sure some companies will be enlightened and not hold it against you but some will. That means less places will hire you, meaning less

It will hurt your career, sure some companies will be enlightened and not hold it against you but some will. That means less places will hire you, meaning less prospects. Are those places you would want to work otherwise? Maybe. That doesn't mean don't testify though, what's more important to you, your career or getting the company punished for what it did?