An assert is there to help you, by alerting you to errors that must never occur in the first place, that must be fixed before the product can be shipped. Errors that do not depend on user input, but on your code doing what it is supposed to do.

Why is assert used?

An assertion allows testing the correctness of any assumptions that have been made in the program. Assertion is achieved using the assert statement in Java. While executing assertion, it is believed to be true. If it fails, JVM throws an error named AssertionError.

Why do we use the assert in testing?

Assertions are used for validating a test case and helps us understand if a test case has passed or failed. The assertion is considered to be met if the actual result of an application matches with that of the expected result.