Ensuring the safety of self-driving cars is naturally important, but neither industry nor authorities have settled on a standard way to test them. Deploying self-driving cars for testing in regular traffic is a common, but costly and risky method, which has already caused fatalities. As a safer alternative, virtual tests, in which self-driving car software is tested in computer simulations, have been proposed. Manually generating such tests will never sufficiently cover the massive amount of driving situations self-driving cars must be tested for; hence, we developed AsFault, a tool for automatically generating virtual tests for systematically testing self-driving car software. We demonstrate AsFault by testing the lane keeping feature of an artificial intelligence-based self-driving car software and causing it to drive out of the road. A video illustrating AsFault in action is available at: https://youtu.be/lJ1sa42VLDw