A backend or database is the most important part of any client/server system. If the backend fails, it may cause data corruption, data loss, system deadlock, and bad performance. Many frontends log on to a single SQL server. A bug in a database may put serious effect on the whole system. Too many bugs in a backend might cost many resources to find and fix bugs and interrupt the system development.
There are so many tests in a frontend which only hit a small area of a backend. Many bugs in database cannot be easily discovered without direct testing. Database testing has several advantages. The database remains no longer a black box to testers. Testers have full control of depth and test coverage. Many bugs can be efficiently found and fixed in the early development stage.
Sometimes it is not very easy to understand and verify the database as compared to a frontend because a frontend generally has intuitive and friendly user interfaces. A backend has its own objects such as stored procedures, triggers and tables. Data integrity and protection is critical. Multi-user support and Performance are big issues. Slowness in operation can result in performance blockages and can be vital to the project’s future. To be able to do database testing, a tester must have strong background in SQL language and server.
Backend test methodology has so many things in common with API testing and frontend testing. Many test methods can be used for database testing. Functional testing and Structural testing are more effective approaches in database testing. They are coincided in some test approaches. However, both the front-end and Back-end Testing methods may find out different bugs, it is strongly mentioned that testers should do both types of testing. There are so many other test methodologies that can be applied to database testing. There are many other test methods that can be applied to backend testing. Some are:
Functional Testing: A database can be broken down into a finite number of testable pieces based on application’s functionality. The main focus remains on functionality of input and output but not on the execution and structure. Different projects have different structures and have different ways to break down.
Structural Testing: A database can be broken down into a finite number of testable pieces based on a Database structure. Tests will check each and every object in a type of structure.
Boundary Testing: Many fields have boundary conditions. For example, in a column for percentages, the value cannot be less than zero and cannot be greater than 100%. We should find out such boundary conditions and analyze them out.
Performance Testing: Performance testing is another important phase of database testing. The performance specifies and measures Query performance. SQL Query Analyzer offers some features also to measure query performance. I have seen developers measure the Query performance during the Unit testing but I can’t find any reason why testers should not do it.
Stress Testing: It involves exposing a database to heavy loads. For example, many users profoundly use the same table that has a large number of records. To build this situation, we need to start as many machines as possible and run the tests again and again.
Other important concerns while doing database testing is that it is a skill demanding job and it requires the widespread knowledge of different databases. This testing requires more perseverance and patience because unlike functional testing, there won’t be enough bugs to find.
I have seen database testing becoming more and more important in those cases when the application under test has to be combined with a third party application having different database. I have personally found database testing very interesting because individual needs vast knowledge of different databases, field mappings and also the possibility of finding project critical data loss bugs. Doesn’t that sound alluring?
There can be many directions to Database/Backend Testing. You have to keep exploring more ways to test the database. If you know of any such ways to make Database testing more interesting, Please do share via your Comments.