1. A computer-implemented method of testing an advertisement for policy violations in a computer system test environment, the method comprising: receiving, in a first computer system, an advertisement to be tested, the advertisement being available for presentation by the first computer system and hosted by a second computer system different from the first computer system; simulating, in the first computer system, display of a visual representation of the advertisement, wherein the visual representation is selectable by a user and wherein the advertisement is associated with an executable code snippet; receiving, in the first computer system, a simulated user click on the visual representation of the advertisement; executing, in the first computer system, the executable code snippet; monitoring, in the first computer system, redirection operations and latency associated with the executable code snippet; in response to monitoring the redirection operations associated with the executable code snippet, calculating a redirection score based on the first computer system requesting first content from a second computer system associated with malware and requesting second content from a third computer system not associated with malware; in response to monitoring the latency associated with the executable code snippet, calculating a latency score based on an amount that the first computer system slows after executing the executable code snippet; calculating an overall score for the advertisement based at least in part on the redirection score and the latency score; and validating the advertisement for service to users based on the overall score.