The Importance of Test Data: How to Generate, Manage and Use Test Data?

What is test data?

Test data could be a commonly used term in the tester’s day-to-day life. While executing test cases, the tester needs some data to input to get the expected output. In order to load a system with data (load testing) or test the breakpoints (stress testing), demonstrate responsiveness and stability (performance testing), or the impacted area (regression testing), etc., huge data may be needed. In simple words “Data used for testing purposes”

Why is it important?

Test data is vital in testing as it determines if an application works as expected. The importance of test data will be understood by this instance, say you would like to check mobile software applications. There are many applications on mobile devices, so to check them you need different files, photos in numerous formats, music files, supported and unsupported formats, video files, contacts files, different emails, etc. are used to test all the applications with the smallest possible data set that has the maximum data coverage to avoid errors.

Types of Test Data

Test data are often classified into the subsequent type:

· Blank files or no data refers to those files which don’t have any data

· Valid set of test data refers to the files supported or accepted by the application. These should give the expected output when given as an input.

· Invalid set of test data refers to any or all the unsupported file formats to determine that the application handles all of them properly without breaking and warns the user with a correct error message.

· Huge test data for Load, Performance, and Stress testing For example, loading an application, requires more than 10000 different format files and this could be either done by an automatic script or with already available test data.

· Test data to test all the boundary conditions includes data that has all possible combinations of boundary values. Boundary values include all those values which are simple enough to handle the application. 

How to Generate Test data?

  • Manually
  • Copy of data from existing production environment
  • Test Data Generation tools

How can we define good test data?

The ideal test data is the combinations of all the test data types so no major defects are missed. Test data should be realistic, valid, and versatile in order to provide maximum coverage. The ideal test data identifies all the application errors with the smallest possible data set. 


Due to the stringent privacy rules and regulations, like GDPR, PCI, and HIPAA, privacy-sensitive personal data is not allowed to use for testing. Preferring to generate synthetic data, comes with its limitations. It’s not always possible to provide enough fake or synthetic data for testing. The quantity of knowledge to be tested is set or limited by considerations like time, cost, and quality.

Test Data Management: How to do it?

Test data management (TDM) is the process of providing high-quality and error-free fine data for testing purposes. It includes many aspects, like removing personally identifiable information and performing data validity checks. 

· Remove any Personally Identifiable Information

Check if your data contains any personal data (PII). If so, apply data masking techniques like substitution, shuffling, or blurring. These techniques facilitate you to form data non-identifiable.

· Perform Validity Check

Performing test data audits regularly to search for outdated data. Additionally, validate if any data is missing and add data to support new features or functionality.

· Refreshing Test Data Regularly

Apart from checking the validity of data, it’s important to regularly refresh the data. Refreshing the test data(regularly updating test data) can improve the standard of the test data and result in the best output when used in testing. 

How to Use Test Data?

1. Identify the need for test data 

Find out the requirements that have been specified and what types of data the system will handle. Examine whether the existing data from the production environment can be reused directly or used after conversion

2. Thorough survey during test design

 Try to determine what kinds of test data is needed, based on the system by setting a meeting with architects and developers at an early stage of designing

3. Creation of test data

Create test data based on the requirements, such as complex data, equivalence partitioning, boundary values, etc., Always duplicate the test data if already present before using it. By this, you can be sure if something goes wrong, you will be able to still access the first test data set

4. Execution of tests cases

Run test cases using all the relevant test data sets that are created.

5. Saving test data

It is important to save the test data which is used so that it is easily accessible in the future

Using the relevant and best test data ensures the testing has the maximum data coverage


Test data is a key component of testing. The choice of test data selected must be re-evaluated in every phase of a multi-phase product development cycle. Test data should be designed in such a way that there is maximum test coverage.

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