Don't fall for that. If the company wants to see if you are a good fit before hiring you they should hire you as a contractor and pay a good hourly rate. Which from my experience in the Bay Area is at least 75 bucks an hour for 40 hours a week.
Remember, this is all at-will employment - either of you can end the relationship at any time. This is where an equity grant/option with cliff vesting comes in. 4 yrs with a 1yr cliff is fairly standard... In other words, if you get fired or leave before 1 yr, you don't get that equity/option and it reverts to the company.