Unit testing, Integration testing and Regression testing

Define Unit testing, Integration testing, Regression testing.

Unit testing:

- Unit testing ensures that each piece of code works correctly.
- It is a software development process where the smallest testable parts of an application known as units are individually and independently scrutinized for proper operation.
- It is automated and can also be done manually.

Integration testing:

- Integration testing ensures each module work together without errors.
- It is a phase in software testing where the individual software modules are combined and tested as a group.
- It generally occurs after the unit testing and before the validation testing.

Regression test:

- Regression test ensures new code did not break previously working code.
- It is a type of software testing which seeks to uncover the new software bugs or the regressions in the existing and the non-functional areas of a system where some of the changes have been made in the enhancements, patches or the configuration changes.