Test data preparation techniques:Test data preparation techniques:

We have briefly discussed the important properties of test data and it also elaborates how test data selection is important while database testing. Now let’s discuss the ‘techniques to prepare test data’.

There are only two ways to prepare test data:

Method 1. Insert New Data:

Get a clean DB and insert all the data as specified in your test cases. Once, all your required and desired data has been entered, start executing your test cases and fill ‘Pass/Fail’ columns by comparing the ‘Actual Output’ with ‘Expected Output’. Sounds simple, right? But wait, it’s not that simple.

Few essential and critical concerns are as follows:

1. Empty instance of database may not be available
2. Inserted test data may be insufficient for testing some cases like performance and load testing.
3. Inserting the required test data into blank DB is not an easy job due to the database table dependencies. Because of this inevitable restriction, data insertion can become difficult task for tester.
4. Insertion of limited test data (just according to the test cases needs) may hide some issues that could be found only with the large data set.
5. For data insertion, complex queries and/or procedures may be required, and for this sufficient assistance or help from the DB developer(s) would be necessary.

Above mentioned five issues are the most important and the most obvious drawbacks of this technique for test data preparation. But if there are some advantages as well:

1. Execution of TCs becomes more efficient as the DB has the required data only.
2. Bugs isolation requires no time as only the data specified in test cases present in the DB.
3. Less time required for testing and results comparison.
4. Clutter-free test process

Method 2. Choose sample data subset from actual DB data:

This is the feasible and more practical technique for test data preparation. However it requires sound technical skills and demands detailed knowledge of DB Schema and SQL. In this method you need to copy and use production data by replacing some field values by dummy values. This is the best data subset for your testing as it represents the production data. But this may not be feasible all the time due to data security and privacy issues.

This strategy deserves one separate post which we’ll discuss in next article ‘Database gray-box testing’ and precautions to take while testing database.

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