Testing data in isolation

There can be several reasons for testing data separately from other applications. In web services testing, you may need to read data from multiple tables and analyze them before actually consuming data through services. Sometimes, it is important to isolate the bugs in a system by calling databases directly. Let's look at the following example:

Service A needs to go through a brokering middleware (data transformer) in order to be compatible with the data formats accepted by Service B. The data transformer is used to transform the data into the format that conforms to the schema of Service B. Suppose a bug that is related to the data handling is uncovered when performing integration testing of services. Such a defect can occur due to an issue at individual services, issue of the logic in data transformer, or data in the database itself. In this type of situation, the testers usually try to isolate the bugs by calling databases through separate SQL client applications...