Applying White Box Testing to Database Applications

Software testing is by far the most popular activity currently used by developers to ensure high software quality. Testing of database applications is particularly crucial as undetected faults can result in unrecoverable data corruption. The problem of database application testing can be broadly partitioned into the problems of test cases generation, test data preparation and test outcomes verification. Among the three problems, the problem of test cases generation directly affects the effectiveness of testing. Conventionally, database application testing is based upon whether or not the application can perform a set of predefined functions. The database application is largely considered as a black box in the testing process. While this is useful to achieve a basic degree of quality, white box testing is required for more thorough testing of database applications. However, the semantics of the Structural Query Language (SQL) statements embedded in database applications is rarely considered in conventional white box testing techniques. In this paper, we propose to complement white box techniques with the inclusion of the SQL semantics. Our approach is to transform the embedded SQL statements to procedures in some general-purpose programming language and thereby generate test cases using conventional white box testing techniques. The steps of transformations and test cases generation will be explained in detail and illustrated using an example adapted from a course registration system. This leads to the identification of additional faults involving the internal states of databases.