Regression testing is essential in the ETL testing process to ensure that existing functionality remains intact after implementing new features, bug fixes, or changes. It should be conducted when new functionality is added, changes are made to existing features, defects are fixed, performance issues are resolved, or the environment changes. Without regression testing, identifying root causes and understanding the product's architecture becomes more challenging and time-consuming.

1. Regression Testing: How It Works

2. What is regression testing?
Regression testing is a critical step in the ETL testing
process. It is a method of testing to ensure that the
existing product works properly with new functionality,
bug fixes, or changes to existing features.

3. When can we perform regression testing?
1. When new functionality comes in.
2. When there is a change request (that is, changes in
existing functionality).
3.When the defect is fixed or when the code is refactored.
4. When there is a performance issue fix.
5. When there is an environment change.

4. Without regression testing, it is more
difficult and time-consuming to
investigate the root cause and the
architecture of the product.
Why is regression testing important?