Detection of defects in an online system includes, for example, receiving, by one or more processor, a plurality of search conditions regarding a search screen of the online system, generating, by the one or more processor, a plurality of test models having factors based on the plurality of search conditions and levels having one or more of the search conditions, generating, by the one or more processor, a plurality of test cases based on the generated plurality of test models having the factors based on the plurality of search conditions and the levels having one or more of the search conditions, and executing, by the one or more processor, the plurality of test cases on the online system to detect defects in the online system.