1. A system comprising: one or more computers configured to perform operations comprising: receiving a plurality of test queries; generating, for each test query, a first group of resources corresponding to a first automated resource selection process and a second group of resources corresponding to a second automated resource selection process, the generating comprising, for each test query: identifying a plurality of resources responsive to the test query, determining, for each resource in the plurality of resources, whether the first automated resource selection process would classify the resource as to-be-indexed or not-to-be-indexed, and then selecting all resources classified as to-be-indexed as the first group of resources, and determining, for each resource in the plurality of resources, whether the second automated resource selection process would classify the resource as to-be-indexed or not-to-be-indexed, and then selecting all resources classified as to-be-indexed as the second group of resources, wherein the determination whether the first automated resource selection process would classify a particular resource as to-be-indexed or not-to-be-indexed is made independently of the determination whether the second automated resource selection process would classify that particular resource as to-be-indexed or not-to-be-indexed.