Database Testing

What is Database Testing?

Over the years, various complex systems have been broken down to specific layers (user interface, business or application layer, data access layer, database layer). To effectively test the application, all the layers need to be tested for what bugs and issues they can introduce into the system. Testing judges what component is responsible for problem and who can fix the problem? In a way, database testing includes testing all components related with database component. A database application has a data access layer which is the code written to manipulate and perform actions on the database. Most database applications are subject to constant change; for instance, business processes are re-engineered, authorization rules are changed, components are replaced by other more powerful components, or optimizations are added in order to achieve better performance for a growing number of users and data. The more complex an application becomes, the more frequently the application and its configuration must be changed. Database Testing is testing at the data access layer, the point at which your application communicates with the database. It is testing the integrity between the database application and its data stores (Stored Procedures, Views, and Tables). The databases and data stores used by the application present a multi-layered system in and of itself. Accessing multiple data stores – has become an integral piece of most applications and it is currently not being tested sufficiently in many organizations.

Database testing is a process working with data that's stored in the database. Database testing, basically, includes the following:- 1. Data Accuracy & Validity (Field size validation) 2. Data Integrity (Check constraints, insert, delete, update)   3. Database Objects (Stored Procedures, Views, Tables)4. Data Migration (Import, Export)5. Data Transaction Consistency and Concurrency (States & Locks)6. Performance related to database (Indices, number of triggers and procedures)7. Security related to database - Data Accessing ( unauthorized access)

Multiple Data Stores:Oracle, SQL Server,

DB2

Intranet Client Computer

Web Client Web ServerInternet

Administrative Application

There are many aspects to the correctness of a database system, including the following:

1. Does the application program behave as specified?2. Does the database schema correctly reflect the organization of the real world data being modeled?3. Are security and privacy protected appropriately?4. Are the data in the database accurate?5. Does the DBMS perform all insertions, deletions, and updates of the data correctly?

Data integrity includes checking constraints. Various constraints that need to be checked are uniqueness constraint, not-Null constraint, composite key constraint and semantic constraint.

Several issues must be considered when checking the database constraints:-

Checking that tables that should not have changed did not change and checking that tables that should have changed did change.

Checking that tables changed in correct way, according to constraints generated and supplied by tester.

Checking that new state satisfies the relevant constraints, including those specified by the tester as well as those defined in the schema and application.

Transaction consistency has two aspects: when run in isolation, it should remain consistent and the relation between old and new state should satisfy the requirements of the transaction's specification. Data Consistency includes both internal and external validations of essential data fields. Internal checks involve data type checking and ensure that columns are of correct types. External checks involve validation or relational integrity to whether duplicate data are being loaded from different files. Transaction concurrency- the DBMS employs sophisticated mechanisms to assure that transactions satisfy the ACID properties - Atomicity, Consistency, Isolation, and Durability - an application can still have concurrency related faults if the application programmer erroneously placed queries in separate transactions when they should have been executed as a unit. There are issues with application programs written in embedded SQL, where multiple clients executing an application program concurrently can have their own host variable. Consistency constraints are violated if more than one instance tries to modify the same data element concurrently. To avoid interference from other instances, related operations should be grouped into a transaction. To improve efficiency, operations on different tables could be performed concurrently. Concurrency problem that occurs when data are manipulated across multiple database transactions is termed offline concurrency problem. Stored procedure or application using the stored procedure should not be left in an unknown situation. It is necessary to implement error-handling mechanism in stored procedures, where in every system thrown error messages will be taken care off. The tester should go through the requirement, as to why the particular stored procedure is written for and check whether all the required indexes, joins, updates, deletions are correct comparing with the tables mentions in the Stored Procedure.  Moreover, he has to ensure whether the Stored Procedure follows the standard format like comments, updated by, etc.

How to test database?

Testing of Database applications requires various tasks:

1. Database schema parsing for extracting information.2. Test database generation.3. Test cases generation.4. Validation of state and output of test cases.

Most methods for generating test databases only consider the database schema or generate random data for a given statistical distribution. However, these generated databases are inadequate to cover many critical execution paths of the application. It is because these generated test databases never take the embedded SQL queries of the database application into account. Consequently, there is a gap between the generated test databases and the queries of the application during test: this leads to the fact that many queries of the application get no (meaningful) results from the generated databases and thus many execution paths of the application cannot be tested. In order to test the critical execution paths of a database application in a meaningful way, a test database generator that considers both the database schema and the queries of the database application during data generation should be used.

Tools used for database testing

CompuWare DevPartnerDB Scandiasoft DBValidator DbUnit SourceForge (also has many db schema comparator tools) Dtm-db- stress IBM Rational Functional Tester 6.1 Open STA MbUnit DBMonster is a tool that generates random test data and puts it into SQL

Database. It helps to test how an application can deal with large database. HTDGen – It generates meaningful test databases for database applications. This

database generator considers both the database schema and the queries of the database application during data generation.

HTTrace – It executes database applications testing efficiently, run regression tests on database applications.

HTPar – It run tests in parallel. Agenda – A (test) Generator for Database Applications. Dbfill and Data factory Genie – database generation

Thanks,Kapil Samadhiya