A policy that governs access to a resource may be tested against real-world access requests before being used to control access to the resource. In one example, access to a resource is governed by a policy, referred to as an effective policy. When the policy is to be modified or replaced, the modification or replacement may become a test policy. When a request is made to access the resource, the request may be evaluated under both the effective policy and the test policy. Whether access is granted is determined under the effective policy, but the decision that would be made under the test policy is noted, and may be logged. If the test policy is determined to behave acceptably when confronted with real-world access requests, then the current effective policy may be replaced with the test policy.