Class AssertionFailure

An unchecked exception representing an Assertion failure.

Assertion failures should be raised when code finds itself in a state that should be impossible. It should not be raised in response to any predictable error condition. Assertion failures indicate that something has gone badly wrong, and that the assumptions under which library code has been developed are not holding.

This extends AssertionError, adding convenient constructors with messages and causes.

Your application may exit due to one of these being thrown. This usualy indicates that something is badly wrong with library code. It should never be raised in response to invalid arguments to methods, or incorrectly formatted data. It is not your fault. Report the error to the mailing list, or who ever else is responsible for the library code you are using. Under some rare circumstances, you may wish to catch assertion failures. For example, when debugging library code, or when the success or failure of an opperation is utterly inconsequential. Ignoring assertion failures out-of-hand is a sure-fire way to make your code buggy. Raise AssertionFailure in your code when something that should be impossible has happened. For example, if you have checked the alphabet of a symbol list you are working with, and somewhere further down an IllegalSymbolException is raised, then this is an assertion failure.